Maehl, who played for Eagles coach Chip Kelly at Oregon, appeared in three games for the Texans in 2011 and spent last year on the practice squad.
Maehl starred for Kelly at Oregon, catching 77 passes for 1,076 yards and 12 touchdowns in his senior season. He signed with Houston as a rookie free agent in 2011.
Menkin originally signed with the Texans as an undrafted free agent and was claimed off waivers by the Eagles last year. He didn't play a down for Philadelphia.