The following info is based on recipes from Joy of Cooking:
General info: Collard greens have large, smooth, dark green leaves and a flavor similar to cabbage, kale or turnip greens, which are all members of the Mustard family. Collards are superb seasoned with only vinegar and hot pepper sauce, but they also have affinities with garlic, onions, chili peppers, lemon and other piquant flavors.
Suggested recipe:
1) Rinse in lukewarm water, strip the leaves from the inedible stalks.
2) Stack leaves, roll them up and slice into very thin strips for fastest cooking. Then chop.
3) Bring 4 cups water and 1 tsp salt to boil in a medium skillet with a lid. Add 1 lb. collard leaves and turn them with a pair of tongs until they wilt down and fit easily in the pan. Cover and cook, stirring occasionally until greens are tender but not mushy (9-11 min. depending on age and thickness). Drain water. Serve with seasonings suggested above.
Daikon radish (and radish greens):
Daikon radishes are harvested in autumn. Unlike spring/summer radishes, daikon radishes are milder in flavor and often pickled, added to soup or grated and cooked with other vegetables and spices. To prepare, trim the leaves from the roots and store separately in perforated plastic vegetable bags. Radish leaves have a shorter keeping life than the roots. The leaves are as tasty and nutritious as turnip greens. Cook them the same way or add them to a tossed salad.
A few daikon radish dishes my family enjoyed:
Pickled diakon
Daikon cake (beware: complex ingredients)
Beef stewed with daikon
Mushroom and daikon soup (we ate daikon with beef bones, but I imagine this recipes is similar)
Good luck with your cooking endeavors, Ben!