My girls love BOXES!! Believe it or not, they go crazy playing with boxes. It starts out as a bathing station, then they peck it all over, then its been turned over and they are standing on it, or in it on its side. It will end up at the other end of the run. I usually leave the box in for 2...
You must be in a nicer climate. We have a foot of snow and below zero windchills...so yeah, my girls dont have any leaves or bugs to scratch at, considering the ground is covered and frozen.
When chickens are cooped up in the winter because of the weather, its best to find them something to do...