Well, I just gave a talk today about groundcovers and showed several thugs. One of them will, indeed, grow in this type of situation...lamium archangel or Herman's Pride. Other lamiums will, too. I stuck some Silver Beacon in around some maple roots without amending the soil at all and it has spread nicely. I do water it some during droughty periods, but just enough to keep it from dying. The Herman's Pride is pernicious if it gets moisture or good soil so you don't want to let it loose in the woods, lawn, etc.

I have two HUUGE!!! Norway maples at the back of my garden which soak up every drop of moisture I give the garden.However I have managed to develop really nice shade beds underneath them. I grow the dreaded variagated Goutweed which is beautifull and has never gone beyond the perimeter I planted it in,probably because of the dryness.I also have Pachysandra, Lamium,Pulmonaria,Sweet Woodruff and Periwinkle in the same beds.I sink large pots into the ground and plant them with impatients or begonias for colour.They look full and lush and I get compliments all the time.My husband laid some soaker hose in the beds so that I can deep water every now and then.With this and lots of compost they are thriving.I hope this gives you some encouragement. Good Luck.

I have several varieties of epimedium growing under my maple tree and I love it. It has pretty flowers in the spring and nice heart-shaped leaves.

a low growing sedum, maybe sedum acre

I second catbird on the epimedium. Just started growing them this summer. They take DRY shade, I'm told, and so far, the one I bought is faring well. If nothing else, you can always grow mint! LOL. Also, I have variegated gold and green ivy. It's not as invasive as the common ivy. Also, liriope, which comes in the regular green, green & gold, and green & white. The regular green is much more invasive than the varigated ones. None of these plants mind the tree roots. I have dry shade and tons of trees all around the perimeter of my yard. If you want, you can also grow moneywort, chameleon plant (invasive nature), and most ferns don't mind tree roots either. That is where they mostly grow naturally is under the canopy of trees. A truly pretty one is the Japanese Painted fern.

Hope this helps and good luck.

Susan

Hellebores would probably do well there if you give them some compost and mulch them; they will need adequate watering until established.