We have a persimmon tree that self-seeds fairly easily, so we told a neighbor he could come dig up some up the small trees and try to transplant them on his property. When he started digging, he got more than he'd expected. Turns out the hillside where the persimmons are growing was a dump site for the old homestead that used to be on our property. He dug out a number of bottles from under the tree roots. Many were broken (there were a few old boots in there, too), but some where unharmed.
Hard to say what else has been buried on our land all these years. Prior to us moving there in 2000, no one had resided in the old (now torn down) house since the mid 70s.