Having mushrooms appear overnight in your potted plants can be disconcerting. The most common mushroom found growing in houseplants is Leucocoprinus birnbaumii, also called the yellow houseplant mushroom. The part of the mushroom seen above ground is the fruit of the larger body of the mushroom; threadlike strands of fungus called mycelium colonize the soil before mushrooms emerge. While these mushrooms may not be attractive, they are only toxic if ingested in large quantities, and if their looks do not bother you, leave them alone, as the mycelium actually breaks soil down and is beneficial to your houseplants. If you do not want mushrooms growing in your houseplants, there are several methods to remove them, though none of them have an extremely high success rate.
Scrape the soil surface of your houseplants. Remove the top 1 to 2 inches of the potting soil and discard. Replace the discarded soil with new, sterilized potting soil. Repeat whenever new mushrooms pop up.
Pick the mushrooms and discard them. Removing the mushrooms removes the spores that generate more mushrooms. Pull out of the soil by the base of the mushroom stems.
Repot your houseplant. Remove your housplant from its pot and shake as much soil off the roots as possible without causing root damage. Discard all of the soil. Wash the container with a solution of one part bleach to 10 parts water. Repot your plant with new, sterilized potting soil.
Soak your houseplant in fungicide. Move your houseplant outside, and apply fungicide to the pot, following manufacturer's instructions. Leave the plant outside until the soil has dried out slightly.