Anise hyssop (blue hyssop) Agastache http://en.wikipedia.org/wiki/Hyssop Region 7b flowers July through September
This is a great bee plant! Save seeds for next year or let them go for themselves wherever the wind and water take them. My personal favorite for honey bees and tea for me!
I thought I had already posted this one here, but I must have overlooked it. http://www.herbs2000.com/herbs/herbs_anise_hyssop.htm
I do think it is, but I have mostly seen the flowers pointing upwards Google shows a few pics just like yours.