The pacific coastal native Americans used Mahonia aquifolium and Mahonia nervosa bark and berries to treat various ailments of the liver, gall bladder, eyes, skin and digestive system. They also used the bark and stems to make a yellow dye for basketry, and I am pretty sure the berries were used for this as well. I have heard of people making wine from the berries. My only personal experience with using the plant for human purposes is making jelly from the berries. Tall Oregon Grape is one of my very favorite native plants because it looks nice year round and the prolific display of spring flowers and summer berries attracts a variety of birds including hummingbirds. It is prickly however.
A good resource book is Plants of the Pacific Northwest Coast by Pojar and McKinnon. It has color photos and for each plant (tree, flower, lichen) it tells what the indigenous peoples used it for. Very interesting to read. For instance, the Tough-leaved Iris was used to make snares for ELK!! I hope I remembered that right.
I live in OR and there are actually three types of Oregon Grape--creeping, low and tall.