Clayton played college football for the Oklahoma Sooners from 2001 to 2004 earning first-team All-American honors twice.

In 2002, he made only one start, but managed 26 receptions for 416 yards, including 5 touchdowns, which tied for the team lead among receivers.

His profile exploded in 2003, as he garnered All-American and All-Big 12 honors after a junior season in which he took aim on the school record book.

[1] The quarterback who threw the passes, Jason White, won the Heisman Trophy, and the Sooners advanced to the Sugar Bowl before losing to national champion LSU.

Clayton's 2004 senior year again netted All-America and All-Big 12 recognition, though his 66 receptions, 876 yards, and 8 touchdowns were not quite as eye-popping as the previous season.

The Sooners again won the Big 12 championship and played for the national title against USC, though they lost in the Orange Bowl.

In his first game as a Ram and having only been with the club less than a week Clayton caught 10 passes for 119 yards (two touchdowns) to lead the team in both categories.

In Week 5, Clayton was placed on injury reserve with a torn patellar tendon in his right knee, which ended his season.

Before the injury, he had emerged as a valued veteran presence on the team, and rookie Sam Bradford's top receiving target.