I have had the experience of finding small items that belonged to something I threw away ages ago and it leaves me wondering why I was holding onto them. Maybe I really AM a hoarder.
Most recently it was a bottle cap. Do I need my head examined or something? I threw out a bottle cap because I didn't know what it was. I make root beer, so I absolutely need a cap for every bottle. Fortunately almost all bottles use the same cap, so I used the cap from the root beer extract to cap my little creation, and I made a special trip to locate a new 2-liter bottle. (I get a steady supply from the neighbors. Always Coke, for some reason.)