Agaricus are in the same family as the store bought button mushroom, portobello, and crimini (Agaricus bisporus). Wild Agaricus species can be very confusing to identify as they can be very similar in appearance.
An Agaricus is what most people think about when they hear the word "Mushroom". It's the textbook mushroom of all mushrooms.
One of the most common mushrooms :)
Agaricus are saprobic meaning they eat dead organic matter.