Ryu, I call this Amanita xanthocephala, but with a little hesitation. If you think see this again in this area, check out the base of the stem for the orange volval margin (see the species description at: http://canberra.naturemapr.org/Community/Species/22398). The cap in your mushroom is pale but you do see this species with washed out cap colours, especially if the mushroom has been exposed to the elements for a while.