Here's what's growing around my coop and run:
Ivy- bad for chickens but they don't eat it (mine).
Butterfly weed- again, bad for chickens but they just don't eat it.
Passion flower vine- they don't seem to eat it- grows like crazy and will cover the trees if I don't prune it back hard.
Blue dawn flower a/k/a house eating perennial morning glory- they don't seem to eat it.
Scarlet runner bean- not really where they can eat it but they are welcome to some beans when it starts flowering and setting beans. (annual, easy from seed).
Nasturtiums- number one favorite flower snack of my chickens. These are growing into the coop and the chickens eat the leaves but not as fast as the plants grow. These are easy from seed and highly recommended- pretty and the chickens love them. You can use the flowers to garnish your salads, too.
Daylilies-chickens show zero interest in eating them.
Goldenrod- just planted. Chickens don't try to eat.
Oxalis- a weed- my chickens absolutely love to eat oxalis and wood sorrel.
Campsis trumpet vine- planted some two months ago, so far chickens not trying to eat it. Should take off and cover parts of the run. (perennial).
I've heard comfrey is good forage food for chickens, just don't have any myself. I've thrown them some spearmint and it seemed to get eaten. Heard of chickens doing well with Salvias.