Once in a while, some mushrooms sprout from my potted plants. This latest one is in the pot with a Alocasia calidora.
I get these every now and then in my plants. They're called Leucocoprinus birnbaumii, and I believe they cause stomach pains or other discomfort if eaten, so I wouldn't suggest trying. They are fun to look at though, mine usually end up dying early though since they pop up in my succulent pots, and I don't water them often enough for the little mushrooms to get very large.
Some of my other pots have some weird mushrooms sprouting too. Wonder where they came from?
Probably just came from spores floating around. They could have come from a plant you bought or just come in through the window. I got some kind of stinkhorn in one of my houseplants years ago, but since then I've only ever seen the yellow mushrooms. They shouldn't cause any harm to your plants, so they're nothing to worry about (unless you have a kid or pet that may eat them). I think they're interesting additions to a potted plant, while they last.