Butler is a cornerback who played at West Alabama, while McCuller is a linebacker from West Texas A&M. Both presumably took part in the team's rookie camp over the weekend on a tryout basis.
The signings, coupled with the team confirming Sunday's reported signing of Maine receiver Derrick Johnson, brings the Patriots' roster to 89 players. Teams are allowed up to 90 players at this time.
The 24-year-old Butler (5-11, 180) began his college career at Hinds (Mississippi) Community College in 2011 before transferring to West Alabama for the 2012 and 2013 seasons. He was an all-conference pick in both seasons and led the conference with 18 passes defended in 2013.
The 24-year-old McCuller (6-2, 240) played in 38 games with 30 starts for West Texas A&M. He was credited with 281 tackles and four forced fumbles over his career.