The veil remnants on the cap do not appear to have the typical warty appearance of those for Amanita muscaria, I can't see any evidence of any form of annulus on the stipe and the second image appears to show a small part of a yellowish volva at the base of the stipe where it has been broken off. Based on the leaves in the image the cap size appears to be in the range of 2-3 cm across, a bit too small for Amanita muscaria. There appear to be no evidence of exotic conifers in the area based on the google image and while there are some reports of Amanita muscaria invading Australian native forests I've not seen that occurring in the ACT. Based on the above I suspect this is more likely to be Amanita xanthocephala.