Found some Agaricus in the Botanic Gardens this morning. They stain yellow, so are in the Section Xanthodermatei, but they are not A. xanthodermus. I doubt they will get a full identification because Agaricus in Australia are rather poorly studied. But anything that stains yellow is off the eating list.

This lot were under some sort of conifer. The oak leaves in the picture are from other trees nearby.

And this lot were under a pin oak.