I can't find my list of dangerous plants and will keep looking. Here is a list of safe plants, though.
Keep in mind that even though the plant may be on this list, you must also be sure that it does not contain any insecticides, pesticides, or fertilizers as well.
Safe and Nutritious Plants:
Alfalfa
Apple
Banana
Barley
Beans
Beets
Blackberries
Blueberries
Broccoli
Brussel sprouts
Cactus
Carrots
Clover
Corn
Dandelion
Grapes
Hibiscus
Kale
Millet
Mustard
Nasturtium
Okra
Parsley
Pea
Pumpkin
Soybean
Spinach
Squash
Strawberries
Sunflower
Timothy
Tomato
Turnip
Wheat
Zucchini
Some plants that I have had success with include:
Parsley
Dandelion
Greens such as: Kale, Mustard Greens, Swiss Chard, Romaine lettuce.
Note: tomato leaves are toxic, even though the tomatoes themselves are not.