Wood chips (of the computer variety).

Science Daily peers into the smoke clouds to see the truth behind biodegradable computer chips make from wood:

Portable electronics — typically made of non-renewable, non-biodegradable and potentially toxic materials — are discarded at an alarming rate in consumers’ pursuit of the next best electronic gadget.

In an effort to alleviate the environmental burden of electronic devices, a team of University of Wisconsin-Madison researchers has collaborated with researchers in the Madison-based U.S. Department of Agriculture Forest Products Laboratory (FPL) to develop a surprising solution: a semiconductor chip made almost entirely of wood.

“The majority of material in a chip is support. We only use less than a couple of micrometers for everything else,”[UW-Madison electrical and computer engineering professor Zhenqiang “Jack” Ma] says. “Now the chips are so safe you can put them in the forest and fungus will degrade it. They become as safe as fertilizer.”