ID from Arora again. Small, fragile, pleated, viscid cap, and cinnamon brown spore print convince me it is Bolbitius. The color is rather variable; usually whitish to brownish but occasionally I see one that is quite yellowish. All were from the same section of lawn nearby, fruiting regularly for several weeks in August. (Sharing lawn with Coprinus disseminatus and Panaeolus foenisecii.) Arora suggests either B. vitellinus (if yellow) and B. lacteus (if whitish). Photos on the web make it clear that the yellow coloration of B. vitellinus is obvious, so I'm tentatively calling it B. lacteus. Is it possible both species are present? More notes here.