If there are fungi growing in the same pot or ground as your succulents and cacti it means that the soil is too moist. The vast majority of fungi (mushrooms, molds, mildew, etc.) … Moisture in the air means there is also going to be moisture in the soil because it evaporates out much more slowly.
Keeping this in consideration, is it bad if my plant grew a mushroom?
Mushrooms growing in your house plants aren’t necessarily a bad thing, but they could be a sign of overwatering, really fertile soil, or just that somewhere along the line some spores got into your plant. They won’t harm your plant.