With vast galactic empires, it doesn't seem all that likely that every world would be like Earth, which can and does produce enough food in its own right for its entire population. Some planets, after enough Blade Runner-esque urban decay and Hive World-esque urbanization, end up becoming little more than immense planet-spanning complexes which, without the necessary Applied Phlebotinum or artificial gardens, would simply not provide enough food to keep their inhabitants from dying of thirst and hunger.
The solution is to have a planet dedicated to the production of food and other naturally-occurring commodities, a purely agricultural world. Or, as the Trope Namer Warhammer 40,000 kindly shortened it, Agri World. An Agri World can be a Single-Biome Planet, but in some cases it seems more likely that the author just described the place as a food production planet and Planet Ville is in effect.
- Deathstalker: Virimonde, the home planet of Owen Deathstalker (the name roughly means "green world" in French) is described as one.
- The Foundation trilogy:
- During the time between "The Psychohistorians" and "The General", the Imperial Capital of Trantor is a City Planet that requires the combined output of 20 agricultural worlds to feed its population of 40 billion people. Ironically, between the events of "The General" and "The Mule", Trantor being sacked several times and the Galactic Empire's fall cutting off its supply lines force Trantor to turn into a purely agrarian society, except for the Imperial Library where the Second Foundation is ruling the First Foundation from behind the scenes.
- Foundation and Empire further mentions agricultural planets in the Pleiades. In The General, Sergeant Mori Luk comes from the Pleiades sector, which has multiple agricultural planets. The only escape from a life of farming is to join the military.
- Hyperion: Renaissance Minor is an agricultural world that provides food to the City Planet Renaissance Vector.
- Known Space: The City Planet homeworld of the Puppeteers has four farm worlds dedicated to growing food for its enormous population.
- Paradox Trilogy: Heaven's Queen has Atlas 35, a planet which Devi states has been "terraformed to within an inch of its life" in order to be a farm planet where every inch of land is suitable for crop cultivation.
- The Thrawn Trilogy: The planet Ukio is primarily an exporter of foodstuffs, and Thrawn takes it over at the start of the third book to feed his ever-growing army of clones. Many, many other such worlds exist in the Star Wars galaxy.
- To the Stars: Earth's colonies are each specialized for a very specific task, and many are dedicated to farming. The idea is that this way none of the colonies have the diverse resources needed to launch a revolt. In Wheelworld, the protagonist is exiled to one such agricultural planet.
- Babylon 5: The Centauri Republic colony world of Ragesh 3 is identified in discussions as an agricultural colony.
- Farscape: An early episode deconstructs this trope. Sykar was forcibly remade into a farm world by the Peacekeepers; the native plantlife was almost completely destroyed to make way for vast fields of Tannot root, and the planet's natives were reduced to all being farm laborers, planting, tending and harvesting the crops. Thanks to the high demand for Tannot root, the farms themselves are steadily being worn out through overharvesting and reduced to barren wastes; the one seen in the episode is said to be the last fertile region of the planet. For good measure, the only thing stopping the Sykarans from noticing any of this is the fact that their food is made entirely of mind-control drugs, and they all believe that every day is the last day before a weekend.
- Stargate SG-1: In "2001", the team visits a planet of farmland that supplies the Aschen homeworld, who turned a gas giant in the system into a second sun and mounted the planet's Stargate on a swivel so grain could be dumped through it more easily. It also turns out they depopulated the planet by giving the original inhabitants medicine that caused sterility.
- In Traveller Classic, planets with specific characteristics could have large portions of their economies devoted to agriculture.
- Warhammer 40,000, the Trope Namer, has quite a few, being host to a huge empire spanning billions of worlds. Their biggest customers are the hive worlds, which are massive planet-spanning cities that would make the entire population of Coruscant weep. Also, since the surface of the planet is mostly fields of crops and grass for grazing, presumably with some scattered forests and orchards, they're probably the most peaceful places in the 40k verse. Of course, it wouldn't be 40k without a grimdark shattering of the peaceful images you're probably getting. QED the siege of Sondheim, a planet-spanning battle between Tyranids and Chaos daemons that ended up consuming the planet.
- Halo: Harvest, as the name implies, is a chiefly agricultural world and covered with extensive areas of farmland. This is not uncommon in the setting — some planets have more hours of daylight than is typical for Earth and happen to have huge tracts of very rich volcanic soil, leading to very large crop yields. Agriculture on such planets is both cheap and productive, and it costs less for other planets to import food from the farm worlds than to grow it locally. This is subverted later as the war rages on, as many of the Outer Colonies where much of the farming goes on are lost, and the Cole Protocol restricts intersteller travel, leading many inner planets to reluctantly take to growing their own food instead of importing it.
- Mass Effect:
- Most of humanity's colonies are pushed into specializing in agriculture, more through accident and necessity than by design. Colonies have a semi-independent status in the System Aliance, so they are expected to be self-sufficient and food is the most important aspect to do that. The government also is more focused on spamming new colonies, so actual development is rather slow.
- Pragia is a failed farm. The batarians had intended to turn the planet into a farm world to feed their empire, but their genetically engineered food crops took to the planet too well, covered it in jungle-like growth and are projected to completely exhaust the soil across the entire planet within centuries.
- Myst: While not planets in sensu strictu, many Ages — tiny, self-contained worlds — served a single economic or social function, often quite narrow. For example, the Age of Teledahn was farmed for a type of fungal spore used in D'ni cuisine.
- Scrap Mechanic is set on a dedicated agricultural planet, staffed primarily by robots to reduce costs and the need for human presence. One can guess where that eventually went.
- Starcraft II: Agria, as the name suggests, is devoted chiefly to agriculture.
- Star Wars: Galactic Battlegrounds: In the Darth Vader campaign, several missions take place on the agri-world of Reytha.
- The "Banks" update changed food from a planet-locked to a "global" resource, enabling players to create specialized planets with all farms.
- The "Utopia" DLC allows one to take the To Serve Man approach with planets populated by other species.
- The "Le Guin" update allows planets to have specializations. Any planet where the majority job is "farmer" gains the "Agri World" specialization, gaining an additional bonus to food production.
- Buzz Lightyear of Star Command: Jo-ad, Booster's home planet, is dedicated entirely to agriculture, resembling the American Midwest and specializing in growing gigantic produce, with the majority of the inhabitants being farmers. It provides the food supplies for Capital Planet. Booster first met Buzz when Zurg tried to steal Jo-ad's entire crop so that he could starve them into submission.