Dandelions are an excellent survival food in part because they are edible and because they are one of the easiest plants to identify and are also very common over much of the country and because all parts of dandelions are edible!
The dandelions flower can be eaten raw and it doesn't taste horrible so that is a big plus. The leaves are also edible and the younger the better. As the leaves get older they get more bitter, still edible just not as tasty. Boiling of older leaves will help remove the bitterness. The roots should always be boiled before eating for taste purposes and you can even drink the water sort of as a tea.