Trifolium variegatum
Bean Family

It's hard to believe that this is a clover because of the flat head of flowers and skinny leaflets (as shown at the bottom left of the picture). However, the flowers are structured exactly like clover flowers, and you'll note that the leaflets come in 3s, just like other clovers. This often grows in lawns, and other disturbed or rocky places. Flowers from mid to late spring.