A little known fact about sunflowers, and other plants in their family, is that their 'flowers' are actually a composite of several to hundreds of flowers. Each '
petal', in fact, is a seperate flower, with one large lobe (called a ligule) sticking off of the side. Each little segment in the middle, which will turn into a single
seed, is its own flower. It is amazingly strange and interesting that a plant would move from having one flower to having many close together, and then the mass of flowers, over time, melded together again to make one large
composite flower containing thousands of individual reproductive structures, and very closely resembling a single flower.
The family in which these plants exist is called Asteraceae, or Compositae in older books, and contains such diverse plants as thistles, dandelions, asters, small trees, and desert-loving plants such as sagebrush.
If you're a plant nerd, and want to use a cheesy line on a girl, you can give a girl a single sunflower and inform her that it is actually thousands of flowers.