Damp all year or just in particular seasons?

Dear Aberdeen:
Sorry, about the 6 month delay in responding to your problem.
If you have sticky clay soil beneath those trees and maybe a undergound spring nearby, just keep on adding compost when you dig a hole For wet free pathways, use large chunks of bark or gravel.. Don’t rake the leaves, except where you want to see the flowers.

Some border plants that can handle damp roots all year as well as shade:

Dutchmans Breeches
Dicentra Alba
Lilies, white – natives do best
Lily of the valley
Trillium, white
Columbine, white
True Solomon’s seal
Violets, white – native species do best
Some varieties of Camellia – ask a Camellia specialty grower for recommendations
Some varieties of Gardenia
Some varieties of Azalea & Rhododendron

Zantedeschia aka Calla, white. May need to be lifted in Fall to prevent it freezing to death.

Bog Iris like Japanese or Louisiana iris, these are available in white shades.

Bacopa, any white one such as Snowtopia or whatever.

Also there are some ferns and Caladiums which have whitish, or variegated with white, foliage that would do well with your conditions.

Will add to this list as I come up with more ideas :)

Dear Aberdeen:
My number 1, moist shade lover is: Fuji Waterfall Hydrangea, it blooms prolificaly in the summer and grows to 5-6’; It trully is a white waterfall.
Monrovia info:
Hydrangea macrophylla ‘Fuji Waterfall’
Unusual white lacecap blooms have double sepals that cascade over deep, dark tapered leaves giving a wonderful waterfall effect. Excellent for the shade garden, containers or as a border planting. Deciduous.

I have Hydrangeas, but not there. Worth a shout. Thanks for all the great ideas.