We can all sleep again at night! The mystery flower has been identified. It is nothing other than a balloon flower, or Platycodon grandiflorus, if you want to get technical about it. I discovered the flower's identity by doing Google image searches till I was blue in the face. The key was including the word "balloon," which you might recall I used in describing the flower to begin with. So in a sense, the answer was staring us in the face the whole time. Go figure. Anyway, if you want to learn more about the beautiful balloon flower, here you go: Balloon Flower.