Preheat oven to 350ºF. Use kitchen scissors, cut open each pita so you have 2 rounds each. Spread butter or margarine on insides of each round. Sprinkle garlic powder, Parmesan cheese, oregano and sesame seeds on top of margarine. Cut the pita rounds into little pieces. Put on cookie sheet. Bake for 5-10 minutes. Cool and serve. You may freeze them, if you wish.