After the first big freeze, the leaves and the black walnuts come down almost all at once. Pick up some walnuts and put them down on the driveway.
Get in your car and drive over the walnuts a few times to break open the outer shell. Put on some old leather gloves, find a bucket to sit on, peel the walnuts.
Wash off the cleaned walnuts, let them dry. Find an old mesh bag and hang the walnuts up for a few weeks to let them cure. Put aside a few hours to shell the walnuts. Now you are a beginner hunter gatherer.