I have two favorites from ARS. One was a guy that bought a house and when he was cleaning out the basement there some some kind of metal thing stuck in the rafters. It turned out to be some kind of battle helmet 500+ years old. The other was a guy who bought a cheap small painting of the Titanic and tucked in the back was an actual lunch menu from the fateful voyage.
Then in the 1970s-1980s, this guy bought a house in a rural area that was owned years ago by a rather successful person. The new owner of the house, bought the contents of the house, though most items were your regular chairs and the like. When he was cleaning out the attic, he found a Parker Bros box with the Invincible inside it. He sold it at auction for several hundred thousand dollars. Every decade or so, the shotgun shows up at auction again and is always purchased by "an un-named person." The last time I saw it up for auction it went for several million dollars. I think several other examples have shown up since that first find, but still.