Caps about 15 mm across. Mt Painter reserve Wildflower Triangle near dam. On old fallen tree trunk (probably eucalypt). Photos 3 and 4 (browner above, white gills) found a week later (22 June 2020) about 10 m away. [Photos 3 and 4 subsequently removed as they were not Coprinellus.]
Photos 1 &2 belong to the Coprinellus/Coprinopsis group and photos 3 & 4 are of a Mycena species, In the former the gills are whitish when young but as the initially pale spores mature and darken (eventually to black) their colour dominates and, given the abundance of spores, makes the gills look brown to black. That colour change occurs fairly early so by the time the caps have fully opened you see dark gills. In Mycena the spores remain pale and mature spores are colourless under the microscope or white when seen in mass (e.g. in a spore print) so they don't dominate and dominate the colour of the gill tissue. In your example the gill tissue is also white but you see Mycenas with coloured gill tissue.