I didn't mean to imply that all teens today are not "nice". I was just shocked when I got a $25 gift certificate to a local restaurant AND and a $30 gift cert to Sports Authority for returning the kids disc. I called him after I received the gifts, and he was insistant that I keep them. He genuinely loves the sport of disc golf, and wants to foster the sense of community in the sport, which I think is important since the sport depends on public spaces and public resources.
As for cost of sending the disc, it only costs about $3 to send a disc via USPS. No big deal.
I'll pay this kindness forward in some way.