If your lawn is showing the signs of a clover patch dotted with yellow flowers, then it is likely that Oxalis corniculata has take root. Oxalis corniculata is the official name for creeping woodsorrel, a plant that resembles clover and has tiny clusters of yellow blooms. The University of California at Davis writes that the name "oxalis" is derived from the Greek word meaning "sour" and refers to "the sour-tasting oxalic acid present throughout the plants."
Creeping woodsorrel leaves are green as well as purple and form a cloverlike shape with three heart-shaped leaves atop a long stem. The leaves drop downward in bright light and during the night.
Creeping woodsorrel's flowers feature five small, yellow petals that are about 1/8 to 1/3 inches long. The flowers form clusters of usually two to five flowers.
Creeping woodsorrel can grow nearly all year. Creeping woodsorrel blooms most extensively during the spring season.
Creeping woodsorrel is easily confused with clover. According to the University of California at Davis, clover is the general name assigned to three plants: "Medicago," "Melilotus" and "Trifolium" -- all of which are troublesome plants for grassy areas. Creeping woodsorrel's greenery has the look of clover leaves.