Try searching for mahonia bealei.

Especially in zone 6, it needs a somewhat sheltered spot away from harsh winter winds.

Partial sun and moist soil is best.

Try Mahonia bealei. The common name I have heard for Mahonia is 'Oregon Grape', which matches your description ;-) Here on the CA coast it likes some shade and is fairly drought tolerant.

I've got a neighbor with an Oregon Grape Holly at the center of her front porch garden - not especially sheltered - and it looks gorgeous year after year. My thought is that until it's established you'll want to babysit it but after that it should do fine. We're considered Zone 5.

Anyone know where to get Mahonia bealei plants locally or by mail order in the Wash DC area?

thanks

I have been growing it for a number of years in Zone 5. I get some winter kill, but in Z6 it should do well. I like it!

Does Mahonia Aquifolium (Oregon Grape Holly) grow in z9ish? Can it tolerate clay in the soil? Does it prefer acid or alkaline soils? Any help would be appreciated...

I bougt my mahonias at home depot(Gaithersburg Md.) last spring-they look great this year & put on good new growth.Mine are planted in full shade,but they get good light & a little sun once the surrounding trees lose their leaves in the fall.

Behnkes in Beltsville MD has plenty. I have three from them last year. THey took a lot of frost/freeze damage and bounced back nicely.

Oregon grape mahonias are usually pretty common in nurseries. If not, try Forest Farms.
FYI, they have some cooler mahonias than oregon grape. Especially one called Arthur Mendiez (sp?). Same blue berries, better foliage.

If you planted it barb, you'll love it come Feb. or March, it puts out a wonderful fragrance from it's yellow flowers.I have 3 plants. They are to die for!! They're also recommended in our area on The Gold Medal Plants list from Pennsylvania Horticultural Society.

Here is a link that might be useful: Gold Medal Plants

I am a new member of GW, and have never posted before, but I felt the need to jump in here, as I have both of the Mahonia plants in this discussion.
Mahonia aquifolium and M bealei have different zone requirements, altho culture is otherwise the same. Also, M. bealei is somewhat a larger plant, I think.
I live in zone 4b and bought a M Bealei that was not marked for hardiness. I have had it for 3 winters, going into the fourth. I have it in a VERY protected place. The rabbits love it, they manage to eat a lot of it every winter, no matter how well I cage it. It would probably be a lot larger otherwise! It is very slow growing for me, but rabbits aside, It probably isn't a bit happy in my zone. I'm actually amazed that it is alive.