I’ve discovered there are two species of yellow flowering Wood-Sorrel (Oxalis) which look very similar, and are often confused.  One is native to Australia, the other is an exotic (weed) originally from South Africa.

Looking at the flowers of both species, I believe this could be the Australian native plant Grassland Wood-sorrel (Oxalis perennans).  Can anyone confirm this?   For reference purposes, the exotic species is Yellow Wood-sorrel (Oxalis corniculata).

yellow-flower-shown-from-above-withleaves-and-soil
This is the best photograph I have of the flower. This was taken at the beginning of April.
yellow-flower-showm-from-above
The flower is a little out of focus in this photograph, but it shows a better view of the leaves. This is a different plant but the photograph was taken on the same day as the photograph of the flower.