First thing I would do is have the soil tested to find out what the PH is. Since there are evergreens I'm guessing its probably acidic. You might need hi-acid loving plants.

How about moss? It can be sooo beautiful.

Well, in our flooded Iowa spring this year, the lamium was very happy and looked great. There's also that creeping jenny type of ground cover -- with a chartreuse variety -- can't recall the name right now. You might look into bog plants and aquatics.
Good luck
Susan

If there isn't standing water in this area, just runoff, my suggestion would be pachysandra aka japanese spurge.

This is probably the third post I've responded to with the same answer - Pachysandra, japanese spurge, but I have to say it's a great groundcover where all else fails to do the job. How it will fare in your zone I cannot comment, but I believe it's hardy to zone 4 and possibly 3.

Pachysandra does great in shade, sun (websites will say otherwise, I have these in both areas - supplemental water in sun/dry areas), and is one of the very few groundcovers to thrive under evergreens.

I have clay soil here and pachy does very well for me.

It is also an excellent choice for erosion prevention - spreads by underground runners, NOT invasive by any stretch of the imagination but will continue to spread outward if not contained (pachy is easily removed and won't start "popping up" all over your yard like other invasives), so I usually recommend a plastic border to keep it confined.

Does great on embankments, loves acidic soil, evergreen for me all year, attractive groundcover. Passersby stop to ask what it is.

It's not a "stepable" groundcover, but you could consider flagstone / stepping stones. Once the pachy are established (and filled in completely), usually within 3 years, those stones won't go anywhere if you incorporate them within the pachy.

Pachy roots are moderately shallow, maybe 5-6 inches, an excellent choice to absorb excess water at the surface. Plant deeper than in the flats to promote more shoots.

They tolerate salt from our snowblower and do just as well for me in full sun and shade. We have a slope at the front of our home where we couldn't get grass to grow (a huge maple towers over), and installed a retaining wall and planted pachy at the base...this is the second year and by next year it will have filled in completely. We planted maybe 6-8" apart.

The ONLY place I could not get these to grow was directly at the base of the maple tree (they grow but don't spread)- the roots of the tree sit at the surface and there's just not enough topsoil there for the pachy to spread runners.

Other groundcovers will be hard to compete with this one - pachy usually wins. The underground runners will choke out anything growing up within it - I used this to rid myself of bishops weed - within 3 years it was completely choked out. Trees and shrubs are fine, but I wouldn't recommend planting with other perennials unless you have them contained - you could incorporate flagstone as a border around other perennials and that would suffice.

Good luck