Canning butter for long-term food storage- I didn't know this was possible! After reading the instructions, I would suggest you use unsalted butter. This is a great idea if you find butter on a loss-leader (selling below wholesale price) sale!
Another pinner wrote: " Homemade Refrigerator Bread and Butter Pickles ~ love these and they are so, so, easy to make! " This links to a site with how-to's and the recipe for refrigerator bread and butter pickles (not preserved, processed, or canned)