How damp? Japanese painted ferns have lovely foliage and I have some Dicentra spectablis Alba that do well in such a position.

I forgot to add that border is quite narrow and have had problems with ferns overhanging onto the grass which causes moss patches. Do love the look of the japanese painted fern though. Maybe I could get a small one. It does stay quite damp and the soil constantly needs digging over as moss patches form very quickly so I imagine it is quite damp. Thanks for your suggestion.

Also, if you haven't already, check out Epimediums for foliage all year and flowers in spring, also Veratrum nigrum has beautifully pleated leaves but takes years to get to flowering size.

Heuchera do well in damp shade in my garden and there are many different colours. I think the paler colours do best in shade.

Solomons seal is also a good plant and then there is mitella, ajuga, persicaria, martagon lilies all thrive in my garden.