Chamaesyce nutans
From Va. Tech
Weed Description: A prostrate summer annual that often forms dense mats that may reach 16 inches in diameter. All parts of the plant emit a milky sap when broken. Spotted spurge if found throughout the eastern half of the United States and also in California and Oregon. This plant primarily occurs as a weed of landscapes, nurseries, turfgrass, lawns, and some agronomic crops.