I'm in England, but there are death caps in Australia, which unfortunately were introduced along with oak trees.

You need an identification guide for your area (Tasmania, or perhaps all of Australia). Unless you can safely identify the species, you cannot be sure it is safe to eat, and should discard it. Identification is usually done using a dichotomous key, which involves checking for the presence or absence of a characteristic (which involves understanding some jargon), then another, until you're down to genus level. Then you check visually to identify the species. It's a bit like an expert system, except printed in a book.

In some countries in continental Europe, you can take wild mushrooms to a pharmacist for identification.