I have someone looking for a single 60"x30" walnut slab. Not looking for anything that needs epoxy work to fill large voids or complete the rectangle. Yeah, I know that’s pretty big for a single piece.
I’ve told them about Live Edge in Duval and Edensaw in PT… anywhere else local? Otherwise looks like it’s all down in Oregon
Walnut is not too common here, but your right California and Oregon has it.
Have you checked https://www.liveedgehardwoods.com/ they are in Duvall, WA.?
Best Selection of large walnut slabs in the Puget Sound is at Edensaw in Port Townsend, they have a large selection of European, American and Carlo Walnut in their warehouse (at least they did about a month ago when I was there) with sizes larger than the size you are looking for.
There is also a place in Ballard called City Trees Furniture (http://citytreesfurniture.com). They salvage trees around Seattle and have a large selection of walnut.