Facing environmentalists' ire, fast-food franchises switched from polystyrene burger boxes to cardboard several years back. Now diners gripe about cold food. U.S. Department of Agriculture researchers are cooking up a solution to make everyone happy: cheap, biodegradable containers derived from a source consumers are more familiar with from buns-wheat. Chemists at the USDA's Agricultural Research Service in Albany, CA, made a foam from the starch inside wheat kernels and mixed it with fibers from wheat stalks to add strength. Boxes made from this foam are as strong as polystyrene containers and insulate far better than cardboard. They're also cheaper than the eco-friendly alternatives now in use-including a similar material made from potato starch. The researchers are close to solving the boxes' main weakness: a tendency to soften when wet. Several companies have expressed interest in the new material; your burger could come in a wheat-based box in two or three years.