Zornia

Zornia dyctiocarpa
Family: FABACEAE
There are quite a few reasons for not being too fussy about having neatly mown lawns. That butterflies breed on grasses is one of them.
Another is that there are a number of pretty little native flowers, too small to be considered as garden specimens, which thrive amongst the grasses.
This little pea-flower is one of them.
A small perennial herb which spreads from a central tap-root, it goes unnoticed for most of the year. Then in summer it sprinkles the lawn with its delightful little flowers. You can identify it by the unusual compound leaf which has two leaflets, as shown in the photo.
Zornia spreads by seed, and can become naturalised over a large patch of sunny lawn. It can tolerate some mowing during the flowering season, but if you are too thorough, and mow too closely, the flowers won’t be able to set seed. It’s a good reason for putting off the chore!