The Terps reached 3-0 for the first time since 2016 in pulling out a scrappy, ugly victory over the Fighting Illini.
Coach Mike Locksley emphasized the importance of his squad playing to their own standards and not to the opponent.
Harrison suffered a season-ending knee injury against Penn State on Sept. 27.
Among other signings, coach Mike Locksley secured five-star wideout Rakim Jarrett.
Boone is the Terps' first four-star recruit in their 2020 class.