I found some parts under the floorboards when doing some wiring - I guess when the part drops it actually travels through carpet by a process of telekinesis never to be seen again - well after 10 years or the next time you pull up the floorboards!
I couldn't remember what the parts where and the models had long since gone too!
I always find that crawling around on the floor under your desk looking for a small model part is a great way of finding the odd woodscrews and dressmaking pins you dropped on the floor earlier!
Oddly the other day I was cutting some 3/64" rivets to length and dropped a few on the floor of the shed (floor of shed = dusty nasty place with cobwebs in corners)
I was a few short so looked on the floor and the rivets were all next to eachother directly under the bench! They were copper rivets - perhaps the properties of this material do not result in the pinging across the room into a parallel dimension as with styrene model plastic kit parts!