I photographed this mushroom cluster about a month ago. They were growing at the edge of a sidewalk near College Park, Maryland. The thick "puddle" next to it, about 40 cm across, had probably been another similar cluster that was then rotting. As I bent over to take pictures, I smelled a strong, but not too unpleasant aroma coming from the rotting mushrooms.
There were many insect larvae squirming around in the soup of rotten mushrooms. I also noticed 1 fruit fly and 1 larger fly loitering around on the mushrooms. The larvae consuming the rotting mushrooms had obviously hatched from eggs laid in situ.
Mike O'Risal, who writes Hyphoid Logic, hesitatingly guessed that the subject mushrooms may be "a very decrepit bunch of something in the genus Gymnopus."