Dave
You can either call or go into Hardwood Industries and ask them if they have any Walnut in the warehouse in the Portland area
There is also Crosscut hardwoods, Woodcrafters, Emerson Hardwoods and Gilmer in the Portland area. I would call them up and see if they can get what you are looking for or have it in stock.
I needed some Ambrosia maple and Woodcrafters brought in 100 Board feet for me. I only need 25 board feet.
There is also the big hardwood store in Klamath Falls.
I would call Felly and ask him what he has. He has been running adds on either Facebook or CL lately. I would also ask Felly if he knows if the guy in LaPine has any walnut for sale. I have bought many boards from him that are well over 12" wide.
Scot