1 cup of cooked Collard Greens = about 230 mg of Calcium. Nutrition wise Collard Green packs a massive punch as it contains Vitamin A, Vitamin C and Vitamin E, Folate, Manganese, Potassium and Fiber.
Other Calcium rich foods include Tofu, Yogurt, Kale, Cinnamon, Sesame seeds, Cheese, Cabbage, Broccoli...
Do you smoke?
If yes - than you should know that research studies indicate that smoking affects or decreases Calcium absorption.