While there are a number of almond / marzipan smelling Agaricus in southern Australia, two separate collections from South Eastern Queensland and Adelaide turned out – via DNA extraction and sequencing – to be 0-1% from Agaricus subrufescens.
More recently a number of collections from NSW and QLD have turned out to also be subrufescens and the species seems quite a common one in Australia with fairly consistent appearance. These commonly stain gold on the cap surface or stem/stipe with age and smell mildly to potently of almonds.
This Agaricus is synonymous with Agaricus blazei which has been commercially cultivated for some time.
Thanks to Jon Atkinson for these photos from this SEQ collection: