The mushroom called “Field Mushroom” is very closely related to the White Button Mushrooms (Agaricus Mushrooms) sold in stores. It grows in North America and Europe from summer to autumn, depending on where you are. They sometimes grow bunched tightly together; sometimes in Fairy Rings.
The cap on mature ones can grow up to 4 inches wide (10 cm.) Like the white mushrooms at the store, when young, a quite white skin covers pink gills. As the mushroom matures and the cap opens, the gills turn brown from the spores being produced.
Maggots often infest quite mature ones. They enter the mushroom from underneath via the spaces between the gills, so there won’t be any apparent maggot holes. Consequently, most people suggest not to bother with the big ones.
They have a very mild taste, very much like the ones from the stores.
Field Mushrooms are very hard for beginning mushroom collectors to gather in the wild because, while they think it looks familiar to recognize without a second thought, there are a few very deadly mushrooms in the wild that also look very much like the white store mushrooms as well.
Called “Field Mushroom” in the UK and in Australia; “Meadow Mushroom” in North America.