What is the coolest thing you have ever found in a property?

[Shiloh Lundahl]

We just purchased a 1920 home to flip in a historic district in Mesa, Arizona.  The house would probably be considered a hoarder house because it was stuffed full of things everywhere.  We rented 3 40-yard dumpsters to haul everything away and that only got about half the stuff.  When I was rummaging through the rest of the stuff I found a belt buckle with a 1896 silver coin from Peru in it.  I really like rare coins so this was an awesome find for me.   

What has been the coolest thing that you have ever "inherited" in a house that you have bought as an investor?

[Mindy Jensen]

A tenant left his baseball collection and comic book collection at our house when he moved out. (I forgot about it until I read this thread.)

I found it absolutely astonishing that someone could put together two separate collections that were completely worthless. Absolutely not one card or comic worth anything. I wasted a lot of time checking into them both.