Do you have mulberries?I also plan to bring in autumn olive. staghorn sumac, beautyberry, american cranberry bush... ill experiment with all of them and see what the chickens love/tolerate.
Any plants that attract a lot of bugs are also something to think about planting for your chicken food forest. Yarrow, lupins, cosmos, marigolds? Sunflower, amaranth... red ripper cowpeas? Cotoneaster is another option because it has late late berries and when flowering is covered in bees and other pollinators!
People and chickens can eat the berries, I think many animals can eat the leaves, and silkworms certainly can eat the leaves (and can then be eaten by chickens or even by people).