There's a place about an hour from us where you can sit out all day in the weather and bang rocks into dust. You get to pay someone for this experience. Truly.
If you are lucky, you find some clear quartz (aka "Herkimer diamonds"). If you are lucky enough to find two decent ones of a similar size, you can have them mounted as earrings (they also do rings, pendants, and other options with whatever finds you want to use). Katie had her two biggest, best, matching stones set as earrings when we took the kids last weekend. Between the three treasure seekers, they found almost as much value in stones as it cost us to drive there and get in the gates, so all-in-all a decent day of family fun. (August and I were relegated to the playground with side trips to the bathroom. Not exactly an ideal place for a 3 year old or crabby mom.)
Now Rob is a bit addicted to the experience. He and Jorge went back for another day of banging on rocks today. I spent the day in various welcome-back-to-school catered receptions. August and Katie spent the day with cousins and Grandma. Pretty much a solid day of winning.