I think you probably need to be a little more specific about that. In particular, it would be useful to say what genre you are looking for (2d vector, 2d painterly, 2d pixel), whether you are willing to pay for it, maybe what kind of license you would prefer and as many things you can say about it.

Especially if you're asking for a free contribution, you should be as specific as you can when making requests.

Perhaps the art made a couple of months ago when someone requested something similar will work for you:

http://opengameart.org/forumtopic/snake-game-art-request