Sagina procumbens

Sagina procumbens is a species of flowering plant. in the family Caryophyllaceae known by the common names procumbent pearlwort, birdeye pearlwort and matted pearlwort. It can be found throughout the Northern Hemisphere and parts of South America. It is a common weed of many environments. It can be found in wild and disturbed habitat, especially moist areas. It can sometimes be seen growing in lawns or in cracks in pavements. This is a perennial herb forming clumps or mats of hairless green herbage, sometimes vaguely resembling a patch of moss. The leaves are linear and up to 1 or 2 centimeters long. The inflorescence is a solitary flower with four or five sepals and four or five small white petals, but the petals are sometimes absent....read more on Wikipedia.