Southern Harebell

I was hesitant to sell one of these flowers at my plant sale because I couldn't remember its name. 

The best I can now determine it is a Southern harebell of the campanula family.  The one in my wildflower book is a bit daintier, but others seem to be this large. 

Previously I had to search for names for comfrey and for Persian cornflower.  They seemed easier to identify.