The 23-year-old winger had been without a club after leaving Barnet by mutual consent in April.
Edgar has said that he wants to impress manager Wayne Burnett.
"It's a great place, there's a great team spirit within the team and everyone wants to do well for each other," Edgar told the club's official website.
"Wayne Burnett has got the team playing a great attacking way so I can see where I can fit in with the squad.
"I've heard Wayne speak to the team about what he wants from the players and the attackers and that's right up my street so I think I can fit in well. I just want to impress Wayne, impress the fans and make my family proud of me."
Edgar, who began his career with West Ham United, has also played for Bournemouth and Yeovil Town.