Looking for a planting

I have a section of my yard that is very dark. It has a huge red maple tree over it, a six foot stockade fence on one side and my house on the over side. For years, dogs used it as a bathroom. I tried buckwheat as a first cover crop with minimal success.
I would like to establish something out there and maybe sporadically let my chickens grace out there but I am open to any ideas.

Thanks!

something that works well for me is aegopoium, silver edge goutweed, it is very invasive but loves loves loves the shade under maple trees..i rake the leaves on top of it every year and it comes back like wild gangbusters !!

it is a beautiful and eible plant..i have tons and tons of it growing here where nothing else will grow..mostly in dense shade..zone 4/5

dense shade under hardwoods: ramps (Allium tricoccum).  they take a while to get going, and they're only in leaf for a short time, but they're very tasty and not too fussy.