When DS was about 10 years old, DH & I took him sledging on a nearby hilly field. After a long, cold afternoon, we trudged home to get warm. But the keys to the house couldn't be found in anyone's pockets. We had no choice but to smash a window and break in cost a fortune to replace. Many months later, DS went camping with his friends to the same hilly field. As they hammered the tent pegs into the ground, they found a bunch of keys. They were ours. 
Things that (sometimes unreasonably) get on your nerves...hopefully lighthearted

. How it got there, I don't know. The only thing I can think of, is that when my friend gave me the gift, the stone fell into the gift bag.
I'm slightly freaked by both these stories.