Not a rock hound myself, so did a search on Lake Superior agates - saw some listings on Ebay, that stuff is worth a buck or two. Arrowheads can fetch a few bucks these days also. My grandparents had a farm in SE MO that had an indian mound on it, used to be able to pick up a lot of broken arrowheads on it when I was a kid. Used to find one every once in a while when chukkar hunting in WA state.