Jenkins, a senior, had 61 tackles and a sack last season. Jenkins made six starts but appeared in 13 games.
As a freshman last year, Matthews played in 13 games as well, posting 28 tackles and a forced fumble.
After a 7-6 campaign that included a victory over Northwestern in the Meineke Car Care Bowl of Texas, the Aggies will be making their SEC debut this season and open the year Aug. 30 against Louisiana Tech.
Information from The Associated Press was used in this report.