We call it "creeping charlie" and it is a very invasive, pernicious weed. The botanical name is Glechoma hederacea.Creeping Charlie 1. It spreads very quickly and easily, it has small purple flowers. Leaf shape may vary some but that is Creeping Charlie, here's another picture of it in bloom.1]1
It looks nothing like the creeping charlie in my lawn - wrong color and growth habit. It may be the very small, invasive Geranium lucidum. If so, the flowers will be pink: https://www.kingcounty.gov/services/environment/animals-and-plants/noxious-weeds/weed-identification/shiny-geranium.aspx.