That particular piece of land might have been a dumping ground? Up at my F-I-L's place, we are constantly picking stuff (glass, metal, cans, nails, bones, etc.) out of his backyard lawn. Areas that had been gone over and over with a fine toothed comb after we initially found quite a bit of glass. He could fill a kitchen garbage bag with the trash he finds every month.
Found out it was a dump back in the 30-40s.
