There is a huge selection of 'leafy' greens which are high in calcium to feed your Dragon, some of which are... kale, argula, collard & mustard greens, parsley, dandelion greens and flowers, endives, radish, carrot and turnip tops, escarole and chicory endive. For more of a variety, mixed into the greens may be many other veggies such as squash, corn, peas, carrots (shredded), sweet potato, cucumber, zucchini, green peppers, chard... also chopped fruit such as cantaloupe, apple, blueberries, peaches, pears, grapes, plums, raspberries... all chopped finely to avoid choking. The main idea in their diet is variety.**Do not feed your dragons iceberg lettuce as is has very little nutritional value and may give the dragon the 'runs' - prompting dehydration.
Dragons will also munch on other greens. If you take your dragon outside or allow it to roam about the house - please be sure to check that the possible munchies are not poisonous.