One morning while reading Barron's, Kara Newman took note of a casual bit of advice offered by famed commodities trader Jim Rogers. "Buy breakfast, " he told investors, referring to the increasing value of pork belly and frozen orange juice futures. The statement inspired Newman to take a closer look at agricultural commodities, from the iconic pork belly to the obscure peppercorn and nutmeg. The results of her investigation, recorded in this fascinating...