We regularly process black walnut - they have a much more pungent, earthy flavor than English walnuts (and much better in my opinion, especially in a carrot cake) .  We load the green golf balls into a sack (old onion or potato sack works great), then run over it about a million times with a tractor or car.  After that, put on a pair of rubber gloves and extract the nuts out of the mess.  Walnut die is one of the most permanent you can find in nature, so don't forget the gloves!  Store the nuts in the basement for a few weeks, then crack them open in a vise.  It will be rare to extract a "whole" nut, most will be in small pieces.  Use a pick to get the meat out, and keep a sharp eye for shell fragments.  After you get all the nutmeat out, look for small shell fragments.  Look again.  And again - those suckers are sharp!  After that, throw the nutmeat in the freezer and use as needed.  Very therapeutic work while sitting in front of the fire on a winter's day.