This is the Dog Vomit Fungus (Fuligo septica) a species of plasmodial slime mold. Slime molds are closely related to fungus, but are not in the same kingdom. Other common names are Dog Vomit Slime Mold or Scrambled Egg Slime. This slime mold feeds on microorganisms that live in dead plant materials. They help with decomposition of dead vegetation, and feed on bacteria, yeasts and fungi. The Dog Vomit Fungus is usually found in soil, lawns, mulch, leaf litter and on the forest floor.
The fluffy yellow Dog Vomit Fungus is the spore-bearing fruiting body of a slime mold; which then degrades, darkening in color, and releases its dark-colored spores. By the end of the day it had shriveled up and turned brown.
The Dog Vomit Fungus is great indicator that my raised bed is full of living, healthy soil. Fungus and slime molds break down plant material to make the nutrients available to feed my plants. The slime molds and mycelium of fungi growing in the soil increase the efficiency of water and nutrient absorption of my plants and confers resistance to some plant pathogens. The slime mold and mycelia are also an important food source for many soil invertebrates.
I am always happy to see mushrooms and even a Dog Vomit Fungus growing at the 40 acre woods.