Ground Geranium or Ground Ivy
This "weed" actually makes for a very nice delicate ground cover. It is a prostrate creeping perennial weed. It is seen as both a solid and variegated plant material. The variegated will lose its variegation in shadier areas. I've used it in containers for a hanging effect. It grows quickly and is very delicate in nature.
This plant will readily root at stem nodes. It also will reproduce from seed.
Although more common in shaded areas in the eastern part of the United States it can be also seen in Missouri, California, the Pacific Northwest, and Alaska. Also occurs in Canada, Europe, and Asia.