There's a grade school playground I hit now and then just trying to get better at identifying coin signals vs. trash since I'm a newbie. I've maybe found a dollar's worth of modern coins in the sand. But this small area with sand but no play equipment has given up at least 50-75 pennies, and nothing else except a Hot Wheels. I named it the Penny Garden because it's like somebody planted them and expected them to grow. New enough to have those weird shield back cents, but they've been there a while. All I can come up with is maybe they let the littler kids dig for "buried treasure" and a lot of pennies got missed. Picked another six or eight out tonight and didn't dig some tones that were probably more.