Trash piles on the front lawn during big trash pickup are good sometimes, I got some flower pot drip trays to use and they are expensive in the stores, the good solid ones. Tell your friend that it's green and resourceful to reuse good items. I wouldn't get down in a dumpster though, nasty sewerage type germs in there, people throw diapers, cat litter, rotting foods, etc. Digging through bags could get you a needle-stick and then you'd be wise to test yourself for hepatitis and HIV.