Yep, dandelion greens are the green leaves from the pesky lawn and garden intruder. Dandelion greens are earthy, nutty, and, quite frankly, bitter. They have a sharp flavor much like radicchio but more so.
The variety of dandelion green cultivated for sale at markets and grocery stores is milder than the intensely bitter and mineral-tasting garden weed. Do note, however, that those "weeds" are perfectly edible, if you want to tame their bitter attitude.
At the market, look for stiff leaves with pointy, fine "teeth." Avoid any bunches of dandelion greens with any yellowed leaves or slime-y stems. In the garden, choose perky green leaves and only use leaves from lawns and gardens that aren't treated with pesticides or other harmful chemicals.
For people who find the bitterness of dandelion greens a bit much, you can always blanch them (cook them briefly in boiling salted water), squeeze the water out of them, chop them and lightly braise them with strong flavors like bacon, garlic, and chiles.
Dandelion greens are also lovely served slightly wilted in warm salads, as long as a strong red wine or sherry vinaigrette and/or rich flavors like a poached egg, toasted nuts, or grated cheese round out their flavors. Try dandelion greens in place of frisée in this classic French bistro salad or in place of escarole in this salad with roasted beets.