This might sound odd, but I get very nostalgic when the seasons change. I have very specific memories tied to the smells of each season. When I go outside and finally smell the Autumn air, I always vividly remember one specific moment from my childhood. I remember when I was a child, back when I would play outside with the other neighborhood kids, we would play a game where we would each try to catch the falling leaves from the trees. Each leaf was considered a scoop of ice cream, and we would yell out what flavor was falling. Catching a leaf let you add that "scoop of ice cream" to your "cone", and the person with the most "scoops" on their "cone" at the end was the winner.
We must have looked ridiculous to anyone nearby, plus we were playing in the middle of the street because that's where the largest trees were, and where the most leaves were falling! (If I had to guess where the idea for the game came from, I believe it was a minigame from Mario Party 5 that we were trying to play in real life!)