I'm sorry for the slow response to this. This one took me a while to work out every thought its not an uncommon weed.
The plant is Verbena bractrata, know as Carpet Vervain. You can find a bunch of information on it here: http://southwestdesertflora.com/WebsiteFolders/All_Species/Verbenaceae/Verbena%20bracteata,%20Bigbract%20Verbena.html
Hope this helps!