This is nifty.
http://www.cnn.com/2004/TECH/12/06/cellphonecover.sunflower.reut/index.html

Materials company Pvaxx Research & Development, at the request of U.S.-based mobile phone maker Motorola (MOT.N), has come up with a polymer that looks like any other plastic, but which degrades into soil when discarded.

Researchers at the University of Warwick in Britain then helped to develop a phone cover that contains a sunflower seed, which will feed on the nitrates that are formed when the polyvinylalcohol polymer cover turns to waste.

This is great timing, since I just got a new i-Mate SP3i SmartPhone today and I'm wondering what to do with my loyal, but outdated, Samsung "DumbPhone." If only I had one of the new phones discussed in the article... then I could throw it out the window on the way home and when the cop pulls me over for littering just explain that I was planting sunflowers.