This is common clover, a low growing annual with stems that root at the nodes - hence its ability to spread like wildfire.
The leaflets have serrated edges and the white flower are produced in clusters at the tips of the stems most of the year round in warmer climates.
This is an important food crop and if you do not have lawn grass anywhere near then it can make an interesting, cottagy alternative.
But beware of annoying the neighbours as it will seed itself easily anywhere closeby.