The white gills don't fit the Cortinarius archeri group. I'm wondering of they were a lilac shade. Then Cortinarius archeri becomes possible, but Lepista nuda is similar (see the comments at https://canberra.naturemapr.org/Community/Species/Sightings/17418). A view of the stem would be useful - to see if there is a veil remanant and any deposited spores (e.g. Cortinarius archeri s.l. on 28 Apr 2017 or Cortinarius archeri s.l. on 21 Mar 2019).