Traditionally, a bride selects a few flowers from her bouquet to press and put in the back of the wedding album. But according to Martha Stewart Weddings, there is no need for the blossoms to remain hidden away when they can easily be framed for display.
After the wedding, select the flowers that look their freshest, and press them for 1 to 2 weeks. Cut mat board to fit your picture frame, and lay it flat on a work surface. Arrange the blooms on the board, then carefully affix each with a bit of craft glue. Let dry, and place in frame. Source