In These Happy Golden Years, Nellie manages to weasel her way into joining Laura and Almanzo on their Sunday buggy rides, Almanzo being completely clueless as to her actual motives (she's out to drive Laura away, either because she's sweet on him herself or just to piss Laura off, or both). Laura, unwilling to cave, lets the edge of the dust-robe (basically a blanket designed to keep dust off the riders' clothes) flap like a sail and scares the horses into bolting. Nellie freaks out along with them - grabs Almazo's arm 'which he very much needed to use just then', throws a fit, and declares she'll never ride behind those maniac horses again. When Laura and Almanzo later take her friend Ida for a drive, Ida is surprised anyone could be afraid of such gentle horses, at which Almanzo looks at Laura, who just smiles and tucks in the dust-robe a little more securely.
Not just that, but shortly after the incident in which the horses bolt, during the same drive, Laura suggests following the road they're on a little farther - because she knows that the first opportunity that they'll have to turn back towards town will take them past the Olesons' claim first. What makes this really amusing is that she makes the suggestion while they've stopped for a brief visit at the claim of some family friends, and Mr. Boast, clearly catching on to Laura's intentions, helps out by cheerfully assuring that "it's a good road straight north." Nellie is very unamused.
At the point where Mary is attending a school for the blind, during a visit home she relates a story of a shopping trip she took with a friend who, while legally blind, can make out colors. Her friend picked out handkerchiefs by color and lead the storekeeper to believe that she could tell color by touch.
It becomes a Crowning Moment of Heartwarming when Laura decides everything she's gone through teaching school is worth it, because when Mary tells the story, it's the first time she's actually laughed since before she went blind.
In These Happy Golden Years, a kitten wanders into church one Sunday morning, and winds up chased by a dog. The kitten runs off and apparently disappears, until Laura realizes it's crawled up beneath her dress and is scaling her hoop skirts like a little mountain climber. When she imagines what might happen if the dog were to find it, she tries so hard not to laugh that Mary elbows her and tells her to behave herself. This just makes things harder for Laura, and when, after church, Mary scolds her for it, she laughs until she cries. When she tells Pa and Mary why, even Mary has to admit it's Actually Pretty Funny.
Also in Little Town on the Prairie, the two drunks that walk arm-in-arm down the street, solemnly singing hymns and kicking the screen doors of every store they pass. Particularly amusing is when they break Royal Wilder's door, and he "yanked it open and said what he thought." Ma doesn't find the story amusing, but Pa (quietly) does.
Almanzo Wilder is faced with the task of proposing marriage to a Tsundere. He rises to the challenge. Keep in mind that, as Laura later points out, they've been courting for three years by now.
Almanzo: "Your hand is so small... [collecting himself] I was wondering if you would like an engagement ring."
Laura: "That would depend on who gave it to me."
Almanzo: "If I should?"
Laura: "Then it would depend on the ring."
The next weekend, when he picks her up for a drive, he slips the ring on her finger— a gold band with a pearl in a garnet setting. She liked it enough to marry him.
In one of the later books, when Laura and Carrie are walking to school, the wind blows Laura's hoopskirts around her legs and she has to constantly stop and twirl around to untwist them. All the while talking about how silly fashions were when Ma was a girl.
When Laura points out that she won't be able to make a wedding dress in time if they get married in a week:
"Wear the one you have on. It is pretty," Almanzo urged.
When Mary and Laura eat wild greens, Mary, who is blind, always asks to make sure there are no bugs on it.
Laura: There are never any bugs! These prairies are so clean! There never was such a clean place.
Mary: You look, just the same. I don't want to eat the only bug in the whole of Dakota Territory.
The fact that Laura takes so long to realize Almanzo's courting her. The reader can see it right off the bat, but Laura's completely oblivious until Mary Power points it out — almost a year into their courtship. Made even funnier by the fact that Almanzo was himself clearly unaware of her oblivion.
In These Happy Golden Years, Almanzo takes on the job of driving twelve or so miles to pick Laura up and take her home for the weekend while she is away teaching school. One of these trips was made in weather well below zero (in the vicinity of forty below), and most of the people they run into on the trip think Almanzo was crazy for making the trip. When Laura asks him why he did it, Almanzo tells her he was looking at the temperature and considering whether it was wise to drive out. Cap Garland walks by, smirks at his obvious romantic dilemma, and tells him "God hates a coward."
Laura: So you came because you wouldn't take a dare?
Almanzo: No, it wasn't a dare. I just figured he was right.