Scour the yard or a nearby park for leaves, then place your favorites inside a thick book for 24 hours to flatten before affixing them to pretty pin boards for some wall or mantel art. Some kinds, such as pin oak and southern magnolia, keep their color naturally; others need a little help. David and Leanne Kesler, co-owners of the Floral Design Institute, in Portland, Oregon, recommend an old-fashioned trick: Iron them. Using medium-low heat, press leaves between two sheets of wax paper until the wax melts, bonding the sheets together. Separate the two pieces; the leaves should come right off.