Definitely Desmodium from the pod. If it is varians, the flowers are very aberrant and much bigger than lifesize, which is 4-5 mm long, and the leaves are much smaller than lifesize, leaflets at lifesize being 5-40 mm long. It would help if you had made field notes of flower and leaflet size.
Thanks Betty, i will try to get back for some measurements. There is a lot of Slender Tick-trefoil flowering here at the moment, and I have added another photo showing the habit of this specimen, which was also unusual to me.