I'd like to know too... Mine play with anything that I put in.. Like food and water bowls. They try to drink water from a watering can sprinkler, pluck all the dandelions out of the ground and run around with them and steal it off of each other.
I've heard of people tying fruit and vegetables to strings or sticking in a frozen
Frozen watermelon to let them peck at, but mine are picky.. Thy won't eat fruit or veggies as snacks. They only want meal worms aside from their feed and grit.
When they hear the bag shake, they try to fly up and snatch it.
I wonder if those Kong balls for dogs would work? Put a treat inside and watch them try to get it out.
There is actually a chicken toy for sale on Amazon (and probably elsewhere)! I bought one, but my chickens haven't arrived yet, so I can't say whether they like it or not. It's basically a chicken version of the dog and cat toys where you put treats inside a ball and the animal has to roll it around and figure out how to get them out.
I also saw in another thread that there are chicken swings. I think there might be a commercially available one, but I'm planning to try to make my own using a branch and rope.