Huitlacoche is a fungus that consumes its host — corn — and transforms it into another food altogether. If you’ve never seen it before, it might be a startling sight. But look beyond the unfamiliar, and you’ll find a treat. In fact, for the past couple of weeks, a scrum of excited chefs has surrounded the McGrath Family Farms table at the Santa Monica farmers market due to the unexpected appearance of fresh huitlacoche (pronounced whee-tla-KOH-cheh), a fungus caused by ustilago maydis, which feeds on ears of corn. Called corn smut or Mexican truffle, the fungus is considered a delicacy...