If you notice orange fungus growing in your mulch, it's likely a stinkhorn, also known as Mutinus elegans. Stinkhorns are very easy to identify because they have a bad odor and have a very phallic shape.
Stinkhorns are penis-shaped fungi that can grow to almost 7 inches tall. They grow out of what appears to be a white egg and are covered with slime. They can be seen growing out of mulch, flowerbeds and white chip piles.
Stinkhorns spread their spores by emitting an odor that attracts flies and other insects. When the insects land on the stinkhorn, the spores stick to them via the slime. The insect then disperses the spores when it moves on.
There is no way to successfully rid your mulch pile of stinkhorns, according to the University of Wisconsin. Getting rid of all your mulch and replacing it with another type of mulch may be the only solution.