All walnut is worth something, as for whether or not it is worth the hassle and trip of getting it to the mill is another story. Unfortunately hard to tell from pictures what sort of visible defects it might have, beyond the obvious it is a yard tree and a lot of mills won't mess with them. There's a couple spots in the bark that from the picture look like it won't make vernier grade to my mostly untrained eyes. I try to ask as many questions of the grader when I'm lucky enough to be on a trip to our local mill to drop off logs though. They will take pretty much any walnut as they are one of the top exporters in the country. Mountains of walnut and ash. Don't know what the current geopolitical public health situation has done to the market, but I can't imagine the amount of shipping containers full of logs are rolling out of there to china like they usually do.