Speedwell, also called Veronica, comes in many varieties. The one pictured stays very low to the ground, covering itself with a blanket of fairly long lasting tiny purple flowers in May. It's been blooming for a couple of weeks now. This patch receives an early dose of dappled morning sun, then a fair stretch of afternoon sun. Not all types of Speedwell are low growing. Some are tall with blue, pink or white flowers. Sometimes they show up in gardens and containers uninvited, but usually as a welcomed surprise. The low growing kinds can actually take a little foot traffic and thus are perfect for growing between pavers. They do well in rock gardens, too, but will enjoy a break from the intense afternoon summer sun.
Also in this photo is the lovely Sweet Woodruff which prefers much more shade than sun. This patch extends away from the sun, receiving only a short span of dappled morning light, then full shade for the rest of the day. Woodruff covers itself with a blanket of white flowers this time of year which lasts at least a couple weeks. But, even after the flowers fade, the plant's pleasant green leaves create a cool meadow feel for the rest of the summer.