I would definitely go with anything that's edible for the chickens, because as the plants grow some of the leaves will be within pecking range. I think an assortment of herbs would be a good choice (plus if you like cooking, you also benefit from it), and you can even let some of them go to flower if you want some flowers in that area.
I've been growing nasturtium outside my run as well but so far the chickens aren't paying it much attention.
I've been growing nasturtium outside my run as well but so far the chickens aren't paying it much attention.