USPS Ferns Forever Stamps - 25 Stamps 25 Forever Stamps in Five designs celebrate the beauty-and popularity-of ferns. Stamps come in folded strip(s) cut from a larger roll. Each of the five stamps depicts a close-up photograph of a different species of fern. Forever stamps are always valid with USPS for first class, one-ounce postage Perfect for invitations, weddings, and general mail.