Tragic Keepsake or Friendship Trinket, the Memento MacGuffin plays a critical role in the story.
Sometimes it's as obvious as a piece of jewelry like an engagement/wedding ring, or a wedding video, or a photograph of a beloved, or a prized heirloom. It can also be a love note or just some small gift, such as a stuffed toy. It can even be a location, such as a childhood home or a favorite corner market, an old building imbued with poignant memories or an entire town. Such a memento can represent romantic partners, deep friendships, familial relationships or even esoteric connections. Whatever the item, and whatever the nature of the relationship, there is a symbolic yet very real form of Synchronization between the Memento MacGuffin and the relationship, and because of that, it tends to also be a #1 Dime.
These items tend to give a lot of exposition and, rather than being true MacGuffins, can play a central role in the plot. Unfortunately, they also tend to be rather luckless. On the other hand, if a character deliberately disposes of the item, it's because It's All Junk. Also, if the character acquires it through a very sad experience, it's a Tragic Keepsake that might be held during a Cradle of Loneliness.
If, however, a character's parents are conspicuous by their absence, or completely unknown, that "treasure" the character carts around with them is probably a specific type of Memento MacGuffin—the Orphan's Plot Trinket. Expect it to be important.
- Blood and Honor: Sanguis has a mask which she inherited from her mother. She begins wearing it early in the story, at Darth Baras's suggestion, and it becomes important to her in several ways - as a physical connection to her past, a means of intimidating her enemies, and a shield behind which she can hide her feelings. It's eventually shattered in an explosion which nearly kills her and she grieves its loss, refusing to wear another.
- Smith's simple denim jacket in The Matrix Slashfic Bringing Me To Life, signifies the beginning of Smith and Neo's fresh start as a couple together. It's even more important to the plot because one of the characters has a Reincarnation Romance Flashback from seeing Smith pull it out and wear it.
- Lydia's spider brooch, which is also a Call-Back to the show, serves as this leading up to the climax in Cinderjuice. BJ is de-powered and almost definitely walking into a fatal trap, but looking at the brooch reminds him why it's worth the risk. The brooch appears at least once in each of the sequels; it's extremely important to Lydia.
- In the Fate/Zero fanfic Fate Zero Sanity, Avenger gives Rin his Casull in the form of a silver cross after he saves her life because she managed to impress him with her courage. She wears it throughout the remainder of the fic and is always shown wearing it afterwards.
- Chapter 5 of the RWBY fic Going Through The Motions makes Blake's bow into this; Adam gave it to her as a sign of his love.
- In Say It Thrice, the wedding ring from the film Beetlejuice serves this function; Lydia suffers from Laser-Guided Amnesia until it's returned to her. A flashback reveals that it originally belonged to Betelgeuse's mother.
- The necklace given to Vale by her sister Maybelle in the Hunger Games fanfic Some Semblance of Meaning. It's not really plot-relevant in any way, aside from the fact that it provides Vale with a tangible link to her family, and she sometimes imagines that clutching onto it gives her some of the fiery Maybelle's strength. In the end, the last time she clutches it before she dies, she thinks that this time, she is "drawing not upon her sister's strength, but on her own."
- Sonic X: Dark Chaos: The red gem that Cosmo wears on her chest is revealed to be a very powerful and rare Doma Emerald that her family kept as a symbol of the Seedrians back on her homeworld. It allows her to communicate with the spirit of her mother Hertia and her father Dark Oak.
- Madoka's ribbons in the Puella Magi Madoka Magica fanfic To the Stars, which have never worn after hundreds of years, one of which Homura has and the other which she gave to Kyouko. The latter resides in the Cult of Hopes main base, open to all magical girls to see. The ribbon is also said to give visions of the future and a glimpse of the Goddess herself.
- Mon Arc-en-Ciel: Turns out that the journal that would eventually become Le Journal de Ladybug was given to him by his mother as he was in the hospital, using as a form of art therapy for his fragile emotional state after what happened to him. This adds a lot more weight to when Nathaniel ripped it up in "Reverser".
- Throughout the Batman Dusk to Dawn novels, Selina Kyle never takes off a pendant with a penny set in it. Damian deduces early on it must be sentimental, and he's right. The coin was a parting gift from her sister Maggie when they last saw each other as girls. It represents their connection, and Selina touches it whenever faced with a moral dilemma. When Maggie returns as a Corrupt Church's Super Soldier, the penny serves as proof that Selina has always loved her, and breaks Maggie's conditioning in time to save her sister's life. After joining the Batfamily, Selina adds to the necklace to represent them: A knight chess piece for Bruce, an enamel bluebird for Dick, a jade carving of a tiger for Damian, and a little cat bell for her daughter, Helena.
- Anastasia has the "Together in Paris" pendant, which is the Orphan's Plot Trinket that unlocks the music box given to her by her grandmother.
- Barbie & The Diamond Castle: Liana and Alexa make necklaces from two heart-shaped stones to represent their friendship, unaware that these stones are actually diamonds from the magical Diamond Castle. After the two have a fight midway through the movie, Alexa takes off her necklace, and becomes susceptible to the villain's magic. Later, Liana replaces the necklace and is able to undo the villain's spell by chanting a friendship mantra they made up earlier while wearing the necklaces.
- The treestar in The Land Before Time is Littlefoot's memento of his mother. It gets crushed by Sharptooth when he attacks.
- Princess Mononoke: The crystal necklace Ashitaka gets from his sister as a (permanent) farewell gift. He gives it to San as a token of affection/remembrance. She later stabs him with it in a fit of despair, but without serious consequences.
- In The Prince of Egypt, Ramses gives Moses a scarab ring to mark his promotion to chief architect. Later, as Moses starts his self-imposed exile, he discards all of the princely trappings from his wardrobe, but can't manage to throw away the ring. He keeps it until he returns to Egypt, then gives it back to Ramses as a symbol that he has returned as an enemy, not a brother.
- William Wallace's ceremonial cloth that he got from his wife. He carries it with him and when it gets lost on the battle ground, Robert the Bruce picks it up and returns it to William.
- Also the thistle, that young Murron gave William at his father's burial. He has kept it pressed in a book.
- "Rosebud", in Citizen Kane. People assume the titular's referring to The Lost Lenore. It's actually a toy sled, owned by him as a child.
- In Guardians of the Galaxy, there's Quill's Sony Walkman cassette player—or, more specifically, the "Awesome mix part 1" tape inside. It inspires him to start a dance-off with the Big Bad at the film's climax.
- The eponymous character of Hancock woke up in a hospital with no memories and no possessions except some gum and two movie tickets quite some time before the start of the movie. He treasures these items, as they're his only connection to the past he can't remember.
- Cobb in Inception uses a top as a totem, which used to be the totem of his dead wife Mal.
- The pinwheel that Fisher finds in his father's safe in the lowest level of the dream.
- Iron Man features his prototype Arc Reactor (originally used to power a medical device keeping his heart healthy) which he wanted to throw away, but his assistant instead puts it in a cute little case, as "Proof that Tony Stark Has A Heart". Comes in damn handy when his more advanced version gets stolen.
- The Evenstar in the The Lord of the Rings movies.
- The Big Bad of Pan's Labyrinth has his father's pocket watch, which he wishes to pass on to his own son.
- Pirates of the Caribbean:
- In Popeye, the titular character carries an empty picture frame with the words "ME POPPA" painted on the empty backing. He kisses it goodnight every night. His father also has a similar empty frame with the words "ME SON."
- The watch in Pulp Fiction.
- According to Word of God, the shoelace necklace that Ramona wears in Scott Pilgrim vs. The World is something that once belonged to her dead younger brother.
- The Spirit movie features this, with the locket given to Sand Saref.
- From the Star Wars prequel trilogy, the japor snippet Anakin gave to Padmé.
- The locket that belonged to Joe's mother in Super 8.
- In Japanese Mythology, a girl named Hachikatsugi-hime is told by her dying mother to always keep a huge wooden bowl on her person, wearing it as a hat. With good reason: the bowl is actually a Bag of Holding that contains all kinds of treasures (kimonos, gold coins, hairpins, etc.) and proves Hachikatsugi's noble heritage. All of it is vital to the plot, since it lets her bypass a Parental Marriage Veto.
- Archer's pendant in Fate/stay night. It's the same one that Tohsaka left on Shirou when she saved his life. He carried it with him his entire life and through death, where it was used as a catalyst symbolizing her that drew Archer to her as her Servant. Also, it's the final proof to Tohsaka's suspicion that Archer and Shirou are the same person from different points in time. He gives it back to her early in the story and Shirou uncovers it, but does not realize its significance.
- Also Sakura's hair ribbon, which was actually the first ribbon ever made by Rin, which she had given to Sakura before her adoption by the Matou family. It is the only real sign of their true feelings for each other (Sakura describes it as only one of two gifts she has ever received from people who are important to her, and after Rin finally realises that she can't kill her sister, she comments that she is glad Sakura had always worn it).
- In Spirit Hunter: NG, Ami's headphones were gifted to her by Yuri shortly before the latter was killed in a supernatural hit-and-run. After Ami herself is kidnapped by the same spirit, Akira uses his Bloodmetry on the headphones to get his first clue to Ami's location.
- When Shiki returns to the Tohno mansion in Tsukihime he brings a white ribbon with him that was given to him by a girl he knew when he was leaving. Bad things happen when Shiki falls for the Twin Switch and gives it to Hisui instead of Kohaku.
- In Cucumber Quest, Sir Carrot and his Love Interest, Princess Parfait, were given special lockets by a wishing star so they could always be together. Carrot's locket is shaped like a strawberry, while Parfait's is shaped like a carrot. After Parfait is kidnapped and held prisoner by the Nightmare Knight, Tomato toys with Princess Parfait's locket, trying to extort a kiss from her. Even Nightmare Knight wasn't amused. The lockets play a huge role in Chapter 3, where they are responsible for Carrot's transformation from a cowardly Failure Knight to a literal Knight in Shining Armor.
- Antimony from Gunnerkrigg Court has a pendant of the alchemical symbol for antimony on a necklace, and a photo of her parents as children. Both have prompted revelations about characters: Reynardine spoke his only unambiguously sincere line upon seeing the necklace, and Annie only has the photo because she stole it.
- The ring in Girl Genius. It even convinces Zeetha that Gil's determination to drag Agatha back to his father is based on real fear that she's the Other.
- From Adventure Time, Marceline's most treasured possession - her stuffed toy, Hambo, was given to her by Simon Petrikov, AKA Ice King, and is a tangible reminder of when he became her guardian as a girl. Naturally, she is furious when her boyfriend trades it for a new wand.
- Avatar: The Last Airbender:
- Katara's necklace, which belonged to her grandmother.
- Also, Zuko's knife, which his uncle gave him and has the words "Never give up without a fight" on it.
- Ron's titanium-reinforced belt in Kim Possible helped Kim remember that they were dating in "Clean Slate."
- The Phoenix Gate (a small, metal plate decorated with the image of a phoenix) from Gargoyles was split between Goliath and Demona as a token of the love they shared at the time. When the halves are joined, it creates a time traveling device.
- My Little Pony: Friendship Is Magic:
- All throughout season 4, the Mane 6 each receive an item from someone they teach their respective elements to. The items are given as thanks, but at the season finale, the items turn out to be keys for the magic box that sprouted from the Tree of Harmony, which grants them Rainbow Power.
- In Twilight's Kingdom Part 2, the medallion that Tirek received from Scorpan before his imprisonment, and gave to Discord before betraying him, proves to be the final key for the chest at the Tree of Harmony when Discord learns his lesson about true friendship.
- The Phineas and Ferb episode "finding Mary McGuffin" revolves around Candace's titular doll being sold at a yard sale and her wanting it back. Dr Doofenschmirtz had been looking for the doll for his daughter Vanessa since she was 7 years old, which gives the doll a lot of sentimental value for her as it proves how much he cares for her. The two fight over the doll until it ends up in the hands of a little girl. Candace decides she's too old for dolls anyway while Vanessa ponders whether she should give up the doll that means so much to her. She doesn't.
- Skydivers wear the parachute closing pin as a necklace. You are allowed to wear it after your first free fall.