Many people see dandelions as weeds, but their leaves and roots actually taste great. Although I will focus on the greens, do not think dandelions are limited to these.
Not all dandelion greens taste good, so you need to know how to recognize the good ones. The first step is to make sure that the plant is not near a road or has had pesticides sprayed on it. Next, if you are going to make a salad, you need to make sure you pick the small, young leaves, as the large, old leaves are very bitter raw.
You can also blanch dandelion and serve it like spinach. For this, you can use either the young or the old leaves, though you still have to make sure the plant isn't by a road or has been sprayed with pesticides. If you do not take this precaution, you risk consequences from bad taste to sickness. Good luck picking your dandelions instead of killing a good tasting, nutritious, herb.