Selling Walnut Trees?

It depends on where they are growing. If they are growing in your yard, lumbermills will not take the chance that there may have been a nail pounded into the trees over the many years it took to grow. Even one partial nail will kill a veneering blade, which is much more expensive to replace than the tree it was cutting. If the trees are in an orchard or forest, then research lumbermills, gunstock producers and firms that produce veneering products. Beyond those, fine furniture making shops where only one or two carpenters work might look for walnut stock, but these are harder to find and might not even be on the internet.

One other idea would be to look for an Amish community nearby and see if they have a carpenter who could use whole trees. My family's farm has a grove of black walnut trees and we were not able to find a buyer for the wood because the grove stands on either side of our lane, with grass growing beneath the trees. From the lumberman's point of view, that constitutes a yard.