Mushrooms or fungi don't make their own food like plants, or move around like animals. That's why mushrooms belong to their own special kingdom of organisms. That means that they eat dead things. Because of their dietary habits, fungi are very important to our ecosystem. If it weren't for them, we'd be up to our necks in litter and garbage.
Fungi come in many shapes and sizes, from the very large to the microscopic.
But what is most important to me is that you can eat them. Commercial mushroom growing is big business in the United States. Commercial growers produce mushrooms in large trays filled with horse manure or a synthetic compost. After a suitable time period, the fungus will produce a mushroom which will appear above the surface and can be harvested. While there are a few species of easily identifiable edible mushrooms, the largest percentage of wild mushrooms are dangerous to eat.