Should I be worried? I was away for 3 days and this thing grew in the soil of my Monstera. Google told me it’s a Shaggy Inc Cap Mushroom, but I’m unsure. How would that get in there? I repotted the Monstera back in March with fresh soil from the hardware store.
It’s an ink cap (coprinus or leucocoprinus) for sure. Mushroom growth, especially this kind, is a sign of a fertile and healthy soil. Don’t worry and let it be.
It could have come from the soil you bought, have been there before, got somehow carried by the wind. There’s no way to tell…