I am not 100% sure, but I believe that my grandma uses ham, (she grinds it herself), pickles/pickle relish, and mayo. There may be something else in there, but she is not good at writing down her recipes.
Grind about 3 cups of ham, or run it through the food processor. Use a little mayo- a couple tablespoons, and a teaspoon or so of mustard to taste, honey mustard works well, add some pickle relish to taste. Chill. Other things you can add if you like are chopped celery or chopped hard cooked eggs.