I have a really nice plant in my yard that was there when I purchased my house. (I live in zone 5.) It is perennial that seems to prefer full sun. It has white blooms in spring. And it has a wonderful licorice scent. Also, it seems to be very resistant to drought.
If you want us to have a better odd of identifying your plant, you should take some marco shots of the foliage, flowers, etc. Given all the data provided by your images, I am guessing that it resembles Cardamine macrophylla.