Platycodon grandiflorus, Balloon Flowerhttp://home.howstuffworks.com/define-balloon-flower.htm
These are a wonderful plant. They look great and the flowers are interesting. It does very well in the zones from 5 and up here in Canada. This particular one was given to me by my Niece for my garden. Actually she has given a few. She lives on Vancouver Island so a real treat for me to have it.
For the very best results and looks it is best to "dead head" the flowers as they finish. That really goes for most plants in the garden.
I find that it does need a cage to help support it as it can get rather tall. It also transplants very easily.