One of the biggest mysteries this offseason was Mario Edwards’ neck injury. The book seems to be closed on that as the Raiders’ defensive lineman went through the team’s first full-contact practice of training camp Sunday and said “it felt great.”

“You think about it,” Edwards said. “But when that first pop happened, I was like, ‘Hey, man, it’s back to football.’ I was ready to go.”

Edwards sprained his neck in Week 15 of his rookie season last year. He wore a brace for months as head coach Jack Del Rio and general manager Reggie McKenzie said they didn’t know the long-term implications of the injury.

Edwards was finally cleared in June, and he was ready Sunday to mix it up.

“It felt good. It was really physical out there,” Edwards said. “I am still getting a little of the rust off. I am focusing on getting better at things that I was focused on when first I got here, like using my hands more and keeping my head out of it.”

Edwards, a defensive tackle and end last year, had 2½ sacks in 10 starts before he tweaked his neck. He might move around even more in this second season under Del Rio and defensive coordinator Ken Norton Jr.

“I’m playing a lot of positions,” Edwards said. “More than I am used to. Playing up, and down with my hand in the dirt. It’s good, really good.”

Briefly: Guard Kelechi Osemele (undisclosed injury) and rookie quarterback Connor Cook (college teammate’s funeral) both returned to practice Monday. … Rookie linebacker Cory James pancaked rookie running back DeAndre Washington in a blocking drill, to the delight of the fans in attendance in Napa. … Del Rio singled out right tackle Menelik Watson, backup guard Jon Feliciano, defensive tackle Jelly Ellis and undrafted running back Jalen Richard as having nice starts to camp. … The Raiders are off Tuesday.

Vic Tafur is a San Francisco Chronicle staff writer.