Actually, there are many types of berries that, while safe for birds to ingest, are poisonous to humans. My rule of thumb: if I can't identify it with one hundred percent certainty as safe, I don't eat it. The Universal Edibility Test is a good (albeit time consuming) way to help determine if a plant is safe to eat (http://www.wilderness-survival.net/plants-1.php#fig9_5). I'd rather play it safe and stay away from mushrooms entirely.