No need to worry, it is simply a harmless fungus triggered by all the recent rain we've had. It's harm to your lawn or plants is purely aesthetic! Yes, it looks pretty gross, but that's as bad as it gets, we promise.
Slime molds are frequently observed when they form large colonies on mulch around trees or shrubs. They may initially appear as a slimy mound or mass, come in a variety of colors, and are often unsightly. Treatment is not necessary.