Mattern's work is held in the permanent collections of the San Francisco Museum of Modern Art, the New Mexico Museum of Art, and the Museum of Fine Arts, Houston, among others. His photographs and exhibitions have been reviewed in publications such as in Artforum, The New Yorker, Camera Austria, and Photonews. He holds an MFA in photography from the University of Minnesota and a BFA in studio art from the University of New Mexico. Currently, he serves as Associate Professor of Photography at Oklahoma State University in Stillwater.