You should look into hydrangeas. They love moist, well-draining soil, do well in partial sun or shade, and thrive in zones 4-9. There are many different kinds of hydrangeas resulting in different size plants. I have a beautiful, blue hydrangea in my front yard and I live on a heavily wooded plot of land. Hope this helps!

Can you add the photo? If you edit in the preview, you have to re-upload the photo.

I put a bunch of bleeding hearts in and called it done because a hundred little ferns poked through after I was done clearing away the top! :)

chelone, ligularia, hosta ,petasites, persicaria just to name a few.

Ferns are the obvious choice. Many would die in the winter and come back, but none have flowers. (They have a completely different reproductive system that doesn't involve pollen...they actually have spores and sperm that swims down the stalk after a rain.)

Jewel Weed is generally considered a weed, but it has pretty orange flowers and likes both swampy areas and shade. Might get over 3 feet, but not much over. Non-toxic to humans (it has medicinal uses).

Various forms of clover might work, like Trifolium wormskioldii (but it would need mowing). Also some ornamental grasses. (Northern Sea Oats).

Astilbe might be a good choice for some fill in color, they like it wet and shady....not sure if they need more than an hour of sun but I think they will do ok in that.

Azalea, boxwood, holly, pulmonaria, hosta, astilbe, ferns, hydrangea, dogwood, Jap. maple-not sure what size you are looking for.

Linda

Lilly of the valley is toxic to dogs. My dog has never touched it but I don't care for it much and has gone from one bed to all over my back yard. I can't get rid of it.

I could have written this post so am watching the answers! I recently lost quite a few plants to root rot in just such a site. They had dwelled there happily for two years then developed the rot after a season of heavy rains :(