I remove the thick husk by driving over Black Walnuts spread on my driveway. Then, after the rock-hard nut shells have dried well, I sit on my porch with a claw hammer, trying to crack them. (No English walnuts here.) Each Black Walnut is more shell than nut meat. After a lot of brutal hammering, I collect the pieces of shell, and work each of them with a small nut pick, to pry the nut meat free of each shell fragment.
I don't just eat Black Walnuts like other nuts. They are way too potent. I further mince the nut meats, place them in a freezer Ziploc bag, and freeze them for sprinkling (sparingly!) onto ice cream or occasionally on a casserole.
But they are nutritious and free and untreated with any chemicals.
Bob