Ken, I concur with Crepidotus as plausible and a good guess as far as probability is concerned. However, the odd stemless Entoloma or two (or perhaps three or four, can't remember at the moment) have been recorded for Australia, often small, but you may want to check out this paper for an exception: https://data.environment.sa.gov.au/Content/Publications/JABG29P041_Catcheside.pdf.