NAPA -- The Raiders signed former Stanford quarterback Trent Edwards on Saturday, four years after they considered drafting him.

As the story goes, the debate heading into the Raiders' 2007 draft was whether to take a quarterback in the first or second round.

One scenario under discussion was to select wide receiver Calvin Johnson with the first overall pick, then come back with Edwards, a Los Gatos product, in Round 2.

Instead, the Raiders took JaMarcus Russell and then followed it up with tight end Zach Miller.

Russell and the $39 million it took to sign him are long gone. Miller, the team's leading receiver for the past three seasons, is an unrestricted free agent whom the Raiders hope to sign.

Johnson was taken No. 2 overall by Detroit and is coming off his first Pro Bowl.

Edwards, after four seasons, two teams and two concussions, is now a Raider and will compete with Kyle Boller to be the backup to starter Jason Campbell.

Although he can't practice until Thursday, Edwards was a spectator at the Raiders' first padded practice of training camp and immediately will immerse himself in the offense of the team he remembers visiting in 2007.

"On the way up here, I had to stop by the facility in Alameda and sign my contract, and the last time I was at that facility was after the combine, right before the draft," Edwards said. "I remember visiting with (former offensive coordinator) Greg Knapp, and I felt like I had a good chance of coming here.

"Obviously I didn't, but now I'm back and excited to be here."

In other personnel news, the Raiders signed free-agent tackle Khalif Barnes to come back for a third season after passing on Jared Gaither over health concerns.

"I want to make sure we're putting healthy players out there," Raiders coach Hue Jackson said. "He's just not where he needs to be to compete on a physical level all the time."

Jackson said Barnes would compete for a starting position, probably at right tackle. Free-agent linebacker Sam Williams signed a contract and returned for his ninth season.

Edwards was a third-round draft pick by Buffalo and started 33 games before being benched Sept. 20 in favor of Ryan Fitzpatrick and waived a week later. Edwards was signed by Jacksonville and spent the season on the bench behind starter David Garrard.

Edwards was considered one of the NFL's best young quarterbacks in 2008, when he went 7-7 as a starter, completing 65.5 percent of his passes for 2,699 yards, 11 touchdowns, 10 interceptions and an 85.4 passer rating.

In Week 3 against Oakland and Russell, Edwards led the Bills to a 24-23 win with two fourth-quarter scoring drives in the last 6:23.

Similar to the beatings Edwards took at Stanford during a 1-10 senior year, the hits began piling up in Buffalo. He left games in 2008 and 2009 with concussions, missing time.

Jackson said his film study with offensive coordinator Al Saunders showed Edwards is "a big, strong, physical guy that can throw the football. Loves the game. He's a gym rat. He likes to study from morning to night."

Edwards came recommended by his agent, Ryan Tollner, who was a quarterback at Cal when Jackson was an offensive coach, and Ted Tollner, who worked at preparing Edwards for the scouting combine and was the Raiders' passing game coordinator last year.

"There were a few other (opportunities) that I could have considered, but with everything going on in this organization, with the head coach, from the top down, this would give me the best opportunity to come in and play for a winning team and sort of rejuvenate my career," Edwards said.

  • Rookie cornerback Chimdi Chekwa left practice after a wrap-up drill because of an apparent shoulder separation or dislocation. Jackson said he didn't think it was serious. Also not finishing was rookie running back Taiwan Jones, who might have strained a hamstring.

  • All three exclusive-rights free agents -- fullback Marcel Reece, defensive tackle Desmond Bryant and linebacker Bruce Davis -- have signed and were on the field, although they can't practice until Thursday.

    The Raiders are awaiting the arrival of restricted free agent Michael Bush. Bush is available to be signed by any team, with Oakland having the opportunity to match the offer or accept a first-round draft pick in return.

  • The Raiders opened their padded session with a man-on-man "Oklahoma" drill and continued to work at a quicker tempo than past years. The first training camp scuffle was between guard Roy Scheuning and linebacker Travis Goethel.

  • Defensive tackle Derrick Hill (Cal) and offensive tackle Cody Habben (Washington) were signed as undrafted free agents. Linebacker Quentin Scott was waived.