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This is from page 108 in the April 30, 2001 issue of BusinessWeek:

Developments to Watch
By Petti Fong

A Greener Way to Pack That Burger

The clamshell containers that hold burgers and other fast-food sandwiches
continue to evolve. First came foamed-plastic containers that were puffed
up using chlorofluorocarbon gas. Decidedly un-green. Cardboard versions
have also made an appearance, but they are expensive to produce and don't
keep food warm for long. Now, scientists at the U.S. Agriculture Dept. are
designing biodegradable clamshells made from wheat. Fiber from the stalk
provides insulation, and starch from the kernel holds the composite together.

Manufacturers already produce environmentally friendly clamshells from
potato starch. But USDA researchers claim there aren't enough spuds in
North America to satisfy the fast-food industry's demand. Wheat-based
containers could fill the bill since the U.S. cranks out more than 30
million tons of wheat each year, much of which is either burned or plowed
under.