Designer Suzanne Lee uses basically a kombucha ferment to press fabric from sugar.2 Fiber can be converted into sugar - that's how probiotics thrive on prebiotic fibers such as the inulin and the sweet-tasting fructooligosaccharides in yacon root3. Lee also suggests we could also use this process to grow furniture.
Eben Bayer was thinking of something less permanent when he suggested replacing plastic with mushrooms.4 Eben has developed a way to manufacture waterproof, shock-absorbent material in any shape he wants from practically any organic waste. Instead of your fragile stuff being shipped with non-biodegradable styrofoam which will break into particles of the same toxic substance, you can put Bayer's mycelium-based packaging onto earth to improve its soil quality; but I'm guessing it won't biodegrade unless you leave it outside. Maybe that's why they use waste cooking oil to make fuel instead of plastic.5