Cooley was released by the Redskins on Aug. 28.
Davis was the team's leading receiver with 24 catches for 325 yards.
"I had a lot of things I wanted to do this year, and I was doing it," Davis said. "It's very discouraging."
Cooley, 30, has spent his entire eight-season career with the Redskins. He has caught 428 passes for 4,703 yards and 33 touchdowns in his career, including eight catches for 65 yards last season.
“The way it looks to me is if something happens here, they would love to have me,” Cooley said when he was released. “If Fred gets hurt or something like that, I think I’d be the guy they sign. I think that.”