What ‘ piece of junk ‘did you find that turned out to be valuable?

I bought a condo in foreclosure some years ago. We weren’t able to go inside, just look outside and put in a bid. My offer won. It was pretty trashed when I went inside that place. I checked all the rooms, calculating the cost of getting them in shape again. I went into the garage at the end of my walk thru and saw there was a car under a tarp.