Hi - I'm just starting up with chickens too and in my run we have irises - those things are tough to remove, so I've left a patch of them. Our chicks are still small 6 & 3 weeks old - they like to play in the iris spikes, but don't eat them. There were a bunch of low growing weeds, but they have completely destroyed them - they are little scavengers! I have heard that Morning Glories are toxic for chickens - I used to grow them in this area so I'm a bit worried...Now I just throw the garden weeds in their pen to keep them busy - they love it!
Good luck!
Good luck!