Only one ring with multiple fruiting bodies. Heino reading your notes for this species am I right in thinking this may have caused the death of a Banksia that used to grow in this spot.
I don't see any evidence of an annulus on the stipe (ring on the stem) which Armillaria luteobalina has. The fruit bodies appear to be closer to Marasmius oreades but I'm not sure.
I'd go for Agrocybe. The species of that genus may have rings but not necessarily robust and they may be intact only in specimens with fairly freshly open caps. On the other hand, the rings may persist. That fits with Michael having seen one ring. The species of the Agrocybe praecox group produce dowdy, brownish mushroom of this size, are reasonably common in spring and (with age) the caps tend to crack in a polygonal pattern. I don't know of this group having caused plant deaths. I have read that another species (Agrocybe parasitica) may be a weak parasite, but perhaps one that can do damage only to a plant that is already weakened by other factors. The fruit bodies of parasitica grow from trunks and I have seen parasitica (or some related species) once in Canberra, growing from the dead end of a lopped branch on (from recollection) an elm. The elm was still alive at least two years later.
Describe how you intend to use these images and/or audio files and your request will be sent to the author for consideration.
Your request has been successfully submitted to the author for consideration.
1,893,037 sightings of 21,044 species in 9,272 locations from 12,889 contributors CCA 3.0 | privacy
We acknowledge the Traditional Owners of this land and acknowledge their continuing connection to their culture. We pay our respects to their Elders past and present.