Whole grains are usually complex carbohydrates-- that means just about anything that hasn't been overly refined. Stone ground whole wheat, oats, brown rice, barley, and quinoa are some ingredients to look for. Avoid anything "white"-- white flour, white rice and other overly processed grains.
Some carbohydrates that take longer for the body to break down are as follows: oatmeal, oats, whole wheat, whole grain, honey whole wheat, barley, fruits, and vegetables.