Boy, that's a tough one. Most gray-foliaged plants prefer sun or even full sun. I can't think of any I've tried that have done well. A lavender once struggled along in partial sun, until I took pity on it and transplanted it.

I've grown convolvulus, with its gray-green leaves and white flowers, in bright shade. And plectranthus argentatus (Brazilian coleus) grows quite well in bright shade, and has very beautiful fuzzy silvery-green leaves with pretty spikes of mauve pink flowers.

I usually stick to plants with variegated foliage to brighten up shaded areas. There are varieties of alpine strawberry, groundcover lysimachia, liriope, and hydrangea that have worked for me. I've also used silvery ferns for a contrast in texture as well as color.

Sorry I couldn't come up with anything, maybe somebody else will have some better ideas.

Japanese painted fern, Athyrium nipponicum 'Pictum' is like hoarfrost on a winter window pane. Brunnera 'Jack Frost' is silver and heart-shaped. Those two are easy to find at garden centers, and (even better) easy to grow. There are books out there on shade gardening and on gardening with foliage, that can provide even more help.

A neighbor gave me a cutting of this plant a couple of years ago and it's very nice. In your part of the country, I would take some cuttings to start indoors over fall and winter. In dark shade they don't grow as well as they will in morning sun or dappled shade. Flowers insignificant but foliage is light silver gray. I have it both in a pot and the ground.

Here is a link that might be useful: Silver plectranthus

How about lambs ear? That's the only name I know it by. It will tolerate some shade, but not dense shade.

I agree with Striped one..I had lamb's ear in dappled shade and it did well for a few years. I have put some in partial shade this year too. Also a neighbor gave me some rose campion that was in pretty deep shade at his house. Am not sure his blooms, but it's nice silver foliage. I think I'll try some in shade this year. Lamium Silver Beacon grows in shade and has pretty shell pink flowers.

how about lamium? there are several varieties; "pink pewter" has silver leaves and pink flower spikes. it's a ground cover that likes moisture and shade.

You may like the hardy perennial Pulmonarias or lung-worts. Most of the cultivars have green leaves spotted with silver, but some newer ones are entirely silver, like the striking 'Majeste'. Pulmonarias take a lot of shade, but are not too thrilled with dryness caused by heavy tree root competition in light soils. This will produce powdery mildew on the leaves, which is not desirable, but it is GRAY!

Some Heuchera or coral-bells varieties also have a lot of gray in the leaves, but this is usually mixed with green, purple or red. You'd need to look at pics to see what may appeal. Heucheras handle dryness pretty well. My favorite is the more subtle variety of our native Heuchera americana called 'Dale's Strain'. I think seeds are available at Chiltern's:

http://www.edirectory.co.uk/chilternseeds/

Ajuga reptans 'Gray Lady' is just that, but it also does not thive in dry soils. Lastly, some variegated Hedera helix (English Ivy) cultivars are also very gray, but often mixed with white in the leaf. This thrives in dry soil and shade.

Here is a link that might be useful:

Japanese Painted Fern; Lamium Silver Beacon; Brunnera Jack Frost; Heuchera Silver Scrolls and Ajuga Gray Lady. I wouldn't recommend Lamb's Ears for more than partial shade, plus the rabbits and squirrels LOVE it.