This was an overnight show... up in the morning (last picture), and over by midday... I think it is an ink cap of some sort growing on wood-mulched garden beds.
Certainly one of the inkcaps - but not a species of Parasola. Your very nice photo of the cap surfaces of the group of 3 mushrooms shows numerous short, white 'threads' on each. These are remnants of a veil that covered the mushroom before it expanded. Parasola lacks such a veil, so this is a species of either Coprinellus or Coprinopsis.