The dry shade under maples is a very challenging planting conditions. I once got some Liriope spicata (not L. muscari) established under a silver maple, but it took a lot of babying.

Are they silver maples? Have the roots created a raised mound surrounding the tree?

Maple trees are stately and beautiful, but to have a maple means not having anything else. I know people will challenge me on that, but I've never heard anyone say that they have lush plantings under an older maple after 5 years. I've even heard people complain that they have trouble with plantings even under Japanese maples!

When I had my enourmous maple, I had some luck with ajuga, but I had to water it more than plants that I had in pots. Watering was difficult because it just rolled off the top of the soil. Feeding and watering faithfully might give you results, but the feeder roots of the maple will moving into the area and take over.

I have 3 large (80')maples (1 each sugar, red, silver) in a East-West row. Planted lamium -- has a lovely silvery foliage and pink flowers. Member of the mint family, but non-invasive. Mine is 2-3" high. Gave it no special attention after the first planting. Spreads at a medium rate.

Sweet William, Hyacinth, dafodils, are the only plants left that still grow under my Sugar Maple root carpet. This year I dug holes to bury pots that I placed a cut piece of landscape paper in the bottom of pot before the drainage gravel and soil. I am gonna plant elephant ears in the pot and mulch around the rim to hide the top of the pot. Hope to prevent the root carpet from choking them out! The roots finally choked out my Hostas, Lillies, and numerous other plants. I plan to try adding more pots each year if it works this Summer. I hope to use this method to prevent my perrenials from getting choked out after a few years of thriving (wasting money on bulbs) and make it easier to dig up those bulbs in Fall that aren't Winter hardy.