If you have never seen one of these, try to find a nursery that sells them. They are Canterbury Bells (Campanula medium) and when they bloom, you cannot see the stem for the flowers covering the plant from top to bottom. As long as you keep the dead/dying flowers picked off, it will bloom for a very long time. If you watch, sometimes you can see the pods where new seeds have developed. Remove them and dry completely out. Store in a cool dry place until the next spring and plant the seeds for that year.
They comes in many colors - white, pink, rose, purple, lilac, and various shades of blue, from very light to very dark. But I prefer the color of the one picture or the dark blue.
They like full sun to light shade, but in the hotter regions, you might want to plant them where they will be gently shaded from noon on.
Try them - you will want to have them in your garden every year!