I went to Lucille Moore Elementary in Panama City and we had a train track right by the school. Under threat of a paddling from the principal to stay away from it, we would put whole rolls of pennies and nickels on the tracks. Crazy results and valuable too. We would sell them, depending on the squashed configuration, for many times the worth of the coins. A flattened silver dollar (not really, but the dollar coin) could bring five bucks. Where any 8-10 year old kid got five dollars in the mid-70's is beyond me. But we made some decent money. Of course you had to wait for the train to get close before you put out the coins or the bigger kids would come through and take it. We always taped them done so they wouldn't vibrate off. Risky all the way around. Unfortunately, railroad tracks were kid magnets in those days. And I do still have my elementary school marble collection. We played for keeps at school (also a reason to be paddled) and I've got quite a collection. A guy at a mineral and gem show offered me $400 for the whole bag a few years ago. I don't know if they make these kind any more, but some of them are real works of art. I declined, the are invaluable to me.