Not worked with walnut in a lonnnng time. But, if I were looking for some, unsteamed, I'd check with local sawmills. There is I believe one sawmill in the phone book. That's in the county seat, about 9-10 miles from me. But there is one more in the county seat, and it is not in the phone book. I did a lot of checking, long ago. The results surprised the heck out of me. Within about ten miles of my home there are seven sawmills, that I tracked down. Which means there are likely some that I did not track down. And, like I said, only one in the phone book. If they cut it, they will likely sell it. May have to let it dry before you use it, but that's no biggie. The way to track them down is to start asking. Ask the grocery store clerk, bank teller, anyone you know, everyone and anyone. Sooner or later you will be able to track one down. And it is likely they can direct you to another, or to someone who knows of one. I'm thinking you will be surprised at how many sawmills of various types are close to you. May be a commercial operation, may be a guy with a bandsaw mill making some money on the side.