Nothing valuable, but I discovered a cache of Matchbox cars, coins, spoons, and small plastic toys all in a small spot in my yard when I first moved in. Seemed cool imaging the kids playing there years prior. Building tunnels in the dirt to drive their cars through and accidentally burying them for me to find later.
Circuit City blew all their money trying to create a disposable DVD called Divx. It was intended to replace video rental stores.