Yellow-staining mushroom

This fairly common Agaricus species is impressive, and often fruits in large numbers in grassy areas and areas of landscaping debris. It is distinguished from similar mushrooms, like Agaricus campestris, by its tendency to stain and bruise yellow and by its characteristic odor, which is phenolic. To see the yellow staining and bruising, rub the mushroom with your thumb--especially near the cap margin and the base of the stem. Importantly, the surfaces that have bruised yellow eventually turn brownish, helping to distinguish this mushroom from others that bruise yellow and remain yellowed. When sliced open, the flesh in the stem base is bright yellow. The phenol smell is sometimes faint, and is best detected by crushing the base of the stem.
It was spotted near Milies train station, Pelion mountain, Greece.