mulberries are the shit. I've heard that if you eat them when they're not yet ripe, they can make you hallucinate. I remember late last summer i saw 2 wood pigeons fall out of a mulberry tree and stumble around because they'd gotten drunk eating the rotten berries, and their feathers were all stained pink, it was quite a funny sight.
Too many elderberries make me feel kinda shitty though, they contain a small amount of cyanide. But the flowers are great for adding to your water. Also, the wood of the elder tree has a very soft inner pith and the shoots are very straight, so you can just hollow them out with a coat hanger or something and make pipes/chillums and blowguns n shit. Very handy tree.