An unusual solution would be to try bamboo. Believe it or not, there are species that are not aggressive, but that will grow in dry shade and around tree roots.

I have a species called Sasa senanensis. It gets about 11' tall, has palm like leaves, and is evergreen in zone 6. It is thriving underneath a large Norway maple that hogs light, rain and nutrients.

There are other species that will do well too - Sasa palmata, Pseudosasa japonica. They are not invasive and require little care. Just snip unwanted sprouts once a year to keep them contained.

The link is for a bamboo nursery that has a good catalog with photos and descriptions. You can look up the species I mentioned above if you're interested in finding out more.

Here is a link that might be useful: Bamboo source