Yes, I've seen mushrooms disappear after a bit if not picked up. Back to the OP though, at most you can double-up on a mushroom... but more than two kids cannot bring back a single mushroom.
--Edit: Actually, I rescind that statement. It seems that, out of all the kids you pile on a mushroom, only half of them seem to actually get the mushroom. I'll play with it more later, but at least it keeps the game running smoothly!
Edited by Zylador (02/17/07 12:11 AM)