Thanks Teresa. There's a related find: Sighting 4680262 found under St John's Wort during the same weeding session. Distinct pink colour so I assumed it was a different species. The tree nearby was Eucalyptus bridgesiana and although most of the grass under the tree is cocksfoot, it is actually a Themeda grassland. Not sure if this helps identifying them.
@Caric thanks for the extra info; love your finds - there are many different species of Australian truffles which are mycorrhizal with many different plants and trees - great finds