His work has been exhibited at the New Mexico Museum of Art in Santa Fe, Silver Eye Center for Photography in Pittsburgh, Photo Center NW in Seattle, the Lawndale Art Center in Houston, Candela Gallery in Richmond, Virginia, and the Photographic Centre Peri in Turku, Finland. Mattern has received awards for his work including the triennial Art 365 Grant and Individual Artist’s Fellowship from the Oklahoma Visual Arts Coalition and the Artist Initiative Grant from the Minnesota State Arts Board. His work is included in the collections of the New Mexico Museum of Art, Photo Center North West in Seattle, BMO Harris Bank, and the Tweed Museum of Art in Duluth. He holds an MFA in Photography from the University of Minnesota and a BFA in Studio Art from the University of New Mexico.