What kind of fungus is this? And how do I get rid of it? :(
Certified GKH Gardening Expert
It appears to be a colony of multiple fungi. One of which looks harmless, but the other could cause you an issue. This is a simple fix for such a small patch.
When you water, just replace 1/4 of that with peroxide. This will take care of the issue. Reapply after a few days if it comes back. After one or two treatments, it should clear off.
Just make sure to let your soil dry out almost completely before watering again. This will keep infections from starting in the soil. Infections are common, and most are harmless, but in this case you can cure this quite easily.