Shortages are overstated. There was less production than in the pre-war period, but America has been producing agricultural surpluses almost continually since the late 1800s. To some degree, rationing was almost more for social control and getting people to think they were part of the system. The big pictures you've seen of them turning in their pots and pans were propaganda. In almost no cases were those of a material quality useful for the war. A few things like rubber/tires, were definitely in short supply, but Americans were never going to run out of food.
edit: Distribution is another matter. Real, localized shortages were possible, so from that perspective, you can't call the rationing system a complete fraud. But it was not as necessary as people would have you believe.
