Baker Mayfield played for Oklahoma before being drafted first overall in the 2018 NFL Draft.
Mayfield began his college career at Texas Tech in 2013, where he became a starting quarterback as a walk-on. He transferred to the University of Oklahoma in 2014 and ultimately became one of the Sooners' most celebrated quarterbacks. Because of transfer-eligibility rules, he did not play during the 2014 season, then started for Oklahoma from 2015 through 2017.
At Oklahoma, Mayfield won the 2017 Heisman Trophy and earned consensus recognition as one of college football's top players. He led the Sooners to major bowl appearances and finished his college career with 14,607 passing yards and 131 touchdown passes.
The usual source of confusion is Texas Tech: it was Mayfield's first college team, but Oklahoma was the school he represented immediately before entering the NFL. The Cleveland Browns selected him with the first pick of the 2018 draft.