Sam is definitely not cutting me any breaks with all this blue plaid. This plaid is mostly blue and white, with very very fine lines of red, yellow, and bright blue weaving through it. It’s got a double seam up the the middle of the breast pockets. It’s western cut with white snaps.
Brand: American Eagle
Sam first wears this shirt in Slumber Party (9x03), at the end of the episode when Sam locks Crowley back up and says goodbye to Dorothy and Charlie.