I put a few snow pea seeds in with my potted pineapple plant hoping something might happen. I didn't expect it to sprout quite so soon though.
Currently it looks like a curly tendril with small leaves. I would almost cal it a bean sprout. more than a sprouting bean plant. It's currently on it's fourth set of leaves and doesn't seem to be stopping any time soon.
I'v also put a black currant seed in there but so far nothing has happened with it.