Chlorophyllum brunneum appears under Casuarina in April-May Sydney. Found in many temperate regions of the world. Closely related to Chlorophyllum nothorachodes, often occurring within a few feet of each other. The stand out feature of this mushroom is the orange oxidization on cutting the stem. Although edible some people are allergic. This mushroom could be confused with Green Spored Parasol, but has white spores or a poisonous Amanita which does have white spores but does not oxidize orange on cutting.
The major characteristic is the bright orange oxidation on cutting the stem, the gills will also stain orange with bruising.
The abrupt bulbous base with ridging is a key feature, particularly in differentiating from Clorophyllum nothorachodes which has a smooth bulbous base. Soil has been brushed off.
Appearance of the ring.
Ring removed and slid over a pen, this procedure helps to better understand the rings attachment to the stem, The ring is like a broad rim hat with a hole in the top.