Yup, I've found a lot of 1930's bottle dumps with my metal detector. Can't resist the urge to dig up all the bottles, plates and cups. Most aren't worth that much, but I have sold some 1930's whiskey bottles for $5 to $10 each.
I find the best bottles to sell are the Bromo Seltzer bottles. To collectors they aren't worth much, but the artsy fartsy crowd, I can get 25 bucks for 5.
And vice-versa, I've found a lot of places to detect by uncovering an old bottle.
Good to know. I'll keep an eye out for them. I know a guy who buys all my 1930's milk glass (mostly cold cream jars). They're a very common find, but he sells them like crazy at a local antiques shop.