This low growing ground cover was seen in Redwood City, CA. It seems that it comes in both the very dark leaves and a green-silver leaf color. The flowers are purple and lavender. Very pretty plant. Last picture shows the lighter color variation.
SOLVED: Please ID
It's buggleweed, aka ajuga. Used as an easy care ground cover in a variety of soils and situations.
Thanks so much for the quite reply, MayPopLaurel! Does the word "weed" at the end mean that it's invasive? I think I might like to plant some of this in my backyard in between large pieces of flagstone. Love the looks of it.
Not a weed to me. I have it on the front edge of a foundation border. Terrible conditions and poor rocky soil. Consider the thickness of your flags if they are part of a walkway because the plant gets around 4" tall when in bloom. Maybe use it along the outside edges and creeping thyme, which is shorter, between flags. If the flags are not a walkway it should be great tucked in.