Green Mushroom (or Fungus)

well, i stumbled on this one this afternoon in my front garden. There were two mushrooms there which were completely white and this one. I think they are of the same type, but this one underwent some kind of mutation.
Don't you just love nature.

I have to admit, it looks very poisonous to me. Quick, hand wash.
Aaah! and some DNA testing to find who's the dad.