I’m guessing Melanoleuca because a few Melanoleucas that I’ve collected in Canberra look much like this. The mushrooms of this genus are a featureless grey-brown with whitish gills, so not much to make them really distinctive to the naked eye. When out and about I might sometimes say “Hmm, looks like a Melanoleuca”, but I’m never happy until I’ve looked under the microscope and, if it is a Melanoleuca, it’s about a 5 second job to confirm that. So, while Melanoleuca is a plausible suggestions, it’s not guaranteed to be correct.