Advice needed for a ground covering plant please.

Hi everyone, I need some advise please.
I'm looking to cover quite a large area of barren, muddy, and shady ground in my garden.
The area I'm looking to cover is underneath an entire bank of trees and so in the summer is very shady and, perversely, in the winter much less shady as the majority of the trees drop their leaves.
I'd like something evergreen, doesnt have to flower but something other than just plain old green would be nice but as the area can be quite difficult to access I'd like something that will cope with shade and dappled sunlight, which self seeds to spread and carpet the area as opposed to growing upward and tall (we rent so I don't want to keep continually paying out for dozens of things to cover large areas,)and something that can pretty much just be left to its own devices.
Any help and suggestions gratefully received, thank you
Heather
Posts
I'd use lamium maculatum http://www.perennials.com/plants/lamium-maculatum-pink-pewter.html
there are lots of different ones with different shades of silver markings, with pretty pink flowers. They're not expensive to buy - by several and plant them about 3 feet apart and they'll spread and spread and carpet the whole area in a couple of years if not sooner.
Here's another of the http://www.crocus.co.uk/plants/_/lamium-maculatum-beacon-silver/classid.3133/
They're so pretty
Dove thank you so much. Just had a look at the link and this would be absolutely perfect. Such a beautiful colour on the foliage and lovely pretty flowers. And perfect on my pocket too! That's exactly wht I was looking for, something I could buy and few of and then leave go.
Off to the garden centre I go....
You could also try ajuga. They have bluish flower spikes and come with dark purplish leaves. I planted 4 last year and they have spread.
http://apps.rhs.org.uk/plantselector/plant?plantid=82
Thank you Gardenmaiden, that looks great too x
Brunnera is tough as nails and will enjoy such a situation. Quite cheap as well which helps.
Thank you Blairs. It looks lovely.
I was going to suggest Brunnera the same as blairs. There is one called something like Jack Frost? which has white edges to the leaves. They also have lovely dainty blue flowers a bit like forget-me-nots.
Jack frost is the one to get Forester2 - I have the bog standard one which is dark green and has slightly larger leaves. Apart from the odd Caterpillar nothing touches it.
I liked the look of the Jack Frost very much, there were lots of images of it on google. Pretty plant.
Bluebells grow in woods / shaded ground quite naturally
You could also try some Green Manure Plants for a few months as this will cover naturally and stop weeds
http://www.marshalls-seeds.co.uk/green-manure-seeds-cid551.html?gclid=COm67dueh7oCFVMdtAod5xsAjw&sort=5