Potential chicken pasture plants

I'm always searching for plants to add to the forest pasture and produce more of our chicken feed on the farm, so I was thrilled to see that Darren has compiled a list of plants for the chicken run on his blog.  While you should go check out the whole list, here are a few highlights that I'm considering adding to our system:

• Darren notes that bamboo is useful for fast-growing shade and wind protection, but we've actually been thinking of planting edible-shoot bamboo in the forest pasture for another reason.  Not only can we eat the shoots and use the heavy canes for light structures, the traditional diet of wild chickens includes a lot of bamboo seeds.
• Jerusalem artichokes (Helianthus tuberosus) are something I've been considering planting for our own table, but am a bit leery of the reports of their invasiveness.  I figure that plants strong enough to be termed invasive are a good choice for the chicken pasture since they'll stand up to heavy scratching.
• I root out burdock everywhere else, but it sounds like the weed is another good choice for the chicken pasture since poultry like the taste of the leaves and the plants are tough to kill.
  

What kind of plants have you found that are able to stand up to the abuse of chicken feet and still provide tasty food for the flock?