Wildflowers of woodland gardens are the most therapeutic to observe and even more so to plant. Plant habit, root structure, moisture needs, aesthetic interest and wildlife connections are key when choosing ground covers.
Sensitive Ferns for example are key plant indicators for water. They would make an excellent habitat in clay-sand, water logged shade spot. Its native habitat is wet, swampy marshy areas. As a taller layer above the sensitive fern, you could try planting Acuba, an evergreen medium sized shrub that can tolerate wet feet, dappled sun or deep shade. These two plant combinations with Azaleas in the backdrop or Viburnums, would be picture perfect. Even better, they would be maintenance free and almost deer proof!
Another layer you could try is a basal layer of Wild ginger (Asarum canadense) which has thick dense roots and attractive heart shaped leaves. It is also a stemless plant, where the leaves form a closely arranged mat leaving no room for exposed ground. As a taller layer behind them, Ostrich ferns would compliment the wild ginger as both these plants have completely different leaves. Loose, large fronds give a much airy and dramatic appearance in the woods, a total contrast to a dense neatly arranged thick mat of wild ginger leaves. Wild ginger at the base, a swath of Ostrich Fern behind it and a group of 'Dexter' Rhododendrons in the backdrop, makes for an enchanted woodland in one single frame!
One last combination you could try would be adding herbs as ground covers to your ornamental garden beds. Sedums, Nastrutiums, Cosmos, Sage, Oregano and other annuals would be prefect for a splash of color or texture. Both in the ground and in planters, herbs add layers of interest.