Mushrooms: Parasites or Fertilizer?

We have these bright yellow mushrooms growing in our potted plant and even in the water collecting dish that pot is standing on. I know how why it is there (lack of sunlight and poor drainage) and we have no pets in the house and everyone is old enough to know not to eat or touch it. My question is whether or not it is good for the plant. So which is it: parasite or fertilizer?