It definitely sounds like slime mold. This mold typically grows on newly ground or chipped wood mulch and generally develops when moisture is plentiful. It won't harm anything and it should disappear on its own when it dries out. There is not much you can do about it other than breaking up and removing any unsightly clumps and backing off on your watering. If it continues to appear despite drier conditions, it may be a signal that your soil isn't draining well. You may need to amend the soil in this area, or watch your watering more carefully. Freshly ground or chipped wood mulch should be allowed to cure for a year before applying.
It may be slime mold. . "(Due to its appearance, some people call it dog vomit slime mold.) Slime molds live on decaying wood or other moist organic matter. To control it, allow the mulch to dry out. Raking the mulch will promote drying"
sounds like fungus/mushrooms due to lack of enough sunshine in that area.