This is a list of plants that other BYC members have had success growing in their chicken run. Remember, chickens have different tastes. What works for someone else might not work for you.
Chicken Proof Plants
Keep in mind that chickens like to scratch, and can uproot small plants. It might be a good idea to make a small fence out of chicken wire to protect small plants until they are large enough to hold their own, or start with a larger plant.
Some of these planst are on the Toxic Plant Chart, but, as other BYC members have pointed out, the chickens generally know what plants to avoid. I have yet to hear of a chicken dying from eating a toxic plant.
Bamboo (once established)
Birds of paradise
Comfrey (mixed results)
Forsythia (mixed results)
Geranium (mixed results)
Grass (Fountain, Pampas)
Honeysuckle (mixed results)
Morning glory vine
Potato vine (mixed results)
Pride of Madeira
Senecio cineraria (dusty miller)
Tomatoes (mixed results with fruit, most won't eat leaves)
Weeds (mullen, poke)
GardeNerd has a beautiful page with pictures from her very lush chicken yard.
new chick 203 Has a more cautious take on things.