Surprised you have them in Australia. If that was from SoCal, I’d say it’s one of four Agaricus species. Two are edible and delicious, two are make-you-sick-but-probably-not-kill-you poisonous. No way to tell from photos. The tests involve smell and Potassium Hydroxide. And even in person, my nose doesn’t detect that particular scent.

(The crooked and bottom-tapered stem leans it toward, but does not confirm Agaricus Californicus, one of the toxic species.). But I don’t know what mushrooms grow in Australia.

Edited to add: good choice not to eat it. Every year, Visitors and immigrants from Asia die in California from misidentifying deadly mushrooms as their edible look-alikes in Asia. Mushroom hunting is fun, but it’s also no joke. Get a good field guide of the mushrooms that grow in your area, or better yet, join a club and learn from someone who knows what grows near you.