Most people know actor Patrick Wilson from his role on the FX show “Fargo,’’ or as the closeted Mormon on HBO’s “Angels in America,’’ or as the handsome dad in director Todd Field’s “Little Children.’’ But before all that, Wilson was on Broadway, something he talked about during an appearance at Harvard the other day. Wilson led a master class for four lucky students, one of whom — senior Laura Peterson— had taken voice lessons from the actor’s mother, Mary K. Wilson. “I’m close with his mom, who’d come to one of my shows [at Harvard], and [Wilson] said he’d be interested in coming to do one of these classes,’’ said Peterson, former president of the Harvard-Radcliffe Gilbert & Sullivan Players. Peterson said Wilson didn’t focus on technique, but on song interpretation: “What’s happening onstage? What’s the character feeling? Who are you singing to?’’ Was she nervous working with Wilson, who earned Tony nominations for his roles in “The Full Monty’’ and “Oklahoma!’’? “Everyone who comes in to do these master classes is there to help you, so it’s a pretty low-pressure situation,’’ said Peterson. “It’s not a scary audition.’’