What’s the most random item you’ve kept for sentimental reasons?

I (a guy) think I still have a small plastic off-brand Lego in my desk. I spent a weekend with my high school crush and we found a bunch of them and had goofy fun with them.

Last I heard she'd moved away, married a woman, and had a successful career in science. I doubt she thinks of me, but I'm glad she did well.