Once established, some ferns are more forgiving. I had Christmas ferns (Polystichum acrostichoides) survive a southern summer of absolutely NO rain but in the shade, of course. They were drying and curling up when Sept. came and hurricanes caused rain in our Piedmont area. Then they revived.

Marginal wood fern (Dryopteris marginalis) also did fairly well although for me it is not wintergreen if it doesn't get summer moisture.

What about green and gold? (Chrysogonum virginianum) It takes shade but blooms better with a little sun. You could put it at the front of the ferns.

Check out some good books, such as Cullina's...for more ideas. Edge of the woods is a great spot for lots of things ONCE ESTABLISHED.

How about partridge berry?

http://www.fs.fed.us/wildflowers/plant-of-the-week/mitchella_repens.shtml

Assuming the trees are deciduous you could try spring ephemerals which belong in your region. For me these are things like bluebells, wild garlic, wood anemones, wood sorrel and celandines. But I am sure there are plenty you could choose from. I also second the ferns suggestion. There are several which will grow in dry shade.

I see a nice woodland wildflower walk there, with ferns, spring blooming bulbs, Jacob's ladder, native phlox divartica, false solomon's seal, and ephemerals under the trees, a few hostas that are species spreading types (not the fancy, water demanding big varieties, but the smaller ones that actually look like wildflowers); other wildflowers that bloom in the shade like blackeyed susans and asters for fall. Shredded hardwood mulch or bark would work well for a walking surface.

I have a dry, shady woodland and all of these plants thrive in it. There are many ferns that do not require a lot of water but actually prefer dry shade. I don't recommend mayapples or true solomon's seal as they can be huge spreaders. Native wild ginger does make a good ground cover, however.

Pussytoes, Antennaria plantaginifolia, might do fine there.