Spotting

I was thinking rachodes, although there are some differences between the ones I have in my yard and this photo

fam agaricaceae
macrolepiota procera (unlikely) - chlorophyllum (previous also macrolepiota) rhacodes or chlorophyllum bohemica--> (rhacodes var. hortensis). you see to which point i will, it's most likely from the genus chlorophyllum ( http://eol.org/pages/22601/entries/34742... ) good luck

pictures of the stem, underside of the gill area and younger buttons? Looks vaguely like one I"m familiar with, assuming it's been raining heavily, but without more id features, I cannot be sure