With pale mauve flowers, that suggests Sherardia arvensis. However, that species has flowers in groups of 4-10 surrounded by 8-10 leaf-like bracts, so that does not fit either.
Hi Betty, FloraVic gives whorls of 4-6 (leaves) for S. arvensis, and doesn't appear to commit to number bracts or number of flowers: however its illustrations show 1 to 3 flowers in group. PlantNet is as you describe. My photos show a congestion of bracts underneath the flowers, rather hard to count: are the 8-10 meant to be in one whorl ? Superficially, the specimen on Ainslie NR is very similar to images of Sherardia arvensis in Flora Vic.
I was quoting from Vicflora. https://vicflora.rbg.vic.gov.au/flora/taxon/fe85ee56-8bb2-4714-b42a-bdf077ee9744 I presume you were quoting from the paper version. Hence the difference. If you have a collecting permit, could you press it and take it to the botanic gardens for a proper ID. I for one do not recognise it at all.