You also can pick ones in your yard, as long as the yard has not been treated with chemicals. Wash the greens well. I cook dandelions the same way I cook any other bitter green. They're best either with big, forceful flavors, such as garlic or anchovies, or played against bland foods, such as pasta or toasted bread bruschetta. Or with a bean soup.
Bean soups are hearty and full of earthy flavor.
They are also adaptable. Or you can make it vegetarian with an olive-oil base. Whichever way you choose, the important thing when cooking bean soup is to take your time. As the water heats, it softens and expands the starch granules, which in turn allows the water to penetrate more deeply into the bean, softening it further. This process has to go slowly for the starch granules to soften evenly.