One of the advantages of council not mowing public reserves. But my iPhone pix went blue/green for some reason - maybe the spores are digital averse. The first pic on the Nikon is the correct gorgeous colour.
You've confused me now!! I'm suspecting it might be an Agaricus sp. by the brown colour coming into the gills (maturing spores) in image three as well as the slight yellowing in the broken bit of stem (stipe) and the thin crowded gills.