The Terps scored three first-half goals and held off a late charge from the Retrievers to remain undefeated.
Freshman Caden Stafford scored the lone goal of the match, opening his Terp career on a high note.
The Terps open their season against No. 18 Charlotte on Thursday.
Vaughn's contract came into effect July 2020 and will run through June 2026, securing the head coach that brought the Terps to the NCAA tournament for the first time since 2017.
Cowles was the second and final Maryland player taken in the draft.
The Terps' former ace is the highest draft pick from Maryland baseball since Brandon Lowe in 2015.
The Terps made their first NCAA tournament appearance since 2017 and established what could become the new culture for Maryland baseball.
The Terps' season comes to an end after struggling to overcome rough pitching performances throughout their elimination game.
One more shot. With the ball carrying to the outfield and landing clear, Justin Vought advanced Randy Bednar home in walk-off…
The Terps dominated in both sides of the game as they launched seven homers and Sean Burke put together a strong start.