We used to dig up God alone knows how many old bottle as we spaded up the garden. We'd put them up on posts or something and throw rocks at them. I may have broken USD 10,000 worth of old bottles in my youth.

The dumps I know of now have homes and buildings on them, but if you can get permission and are willing to dig a few feet down I'll bet you could uncover 'most anything. My brothers and I once dug a hole -- just because it needed digging -- and removed the entire roof of a Model T Ford in doing so (along with MUCH other debris).