I bought a piggy bank at a yard sale for 50 cents. Shaken, you could hear something inside, but the owner couldn't figure out how to open it. It had one flat-head screw holding it together. I opened it when I got home and there was $2.87 in Canadian coins, including 6 silver dimes. The oldest was a George nickel.
Three years ago I bought another piggy bank and shaken you could hear a mushy sound (not coins). When I opened it there were 2 halves each wrapped in $5.00 bills. Not bad for a quarter!
I bought a US silver dollar, 1889, for $5.00. It was on a very tarnished belt buckle. I took it off the buckle and threw the buckle in the trash. Its' value then was around $35.
There are coins in the ground and all kinds of places. All you have to do is look for them.
Scrapping; you know, like melting them down. The copper in a penny is worth more for scrap, than the penny! But if you melt them it's Destruction of US coins.