The Dallas Cowboys star says he's not done stackin' up college degrees ... revealing his plans to hit the books and pursue a PhD in psychology!!

The NFL's Rookie of the Year -- who already has his Bachelor's AND Master's degree from Mississippi State -- joined the Talk of Fame Network to discuss his desire to keep learning both on and off the field.

"Just getting my degrees has helped me immensely, just within the game of football and with people, just making me more educated in general," Dak says.

"It's something I continue to do. I'm actually continuing at some point either when I'm done (playing) or one offseason, I want to start working on my doctorate. So, I mean, it's very important to me."

Cool stuff at the 2 minute mark ... especially coming from someone who dominated his first year in the league.