The three-star product joins the Terps from nearby St. John's College High School.
The former All-Pro running back likened McFarland to a former Steeler great.
The 2020 4th round draft pick could see the field a lot as a rookie.
Ellis racked up 52 tackles and 22 pass deflections during his four years in College Park.
Brooks earned second team All-Big Ten honors in 2019.
McFarland rushed for 1,636 yards and 12 touchdowns during his two seasons in College Park.
Four Terps could be taken in the draft's late rounds.
Castleberry didn't receive a carry for Michigan last season.
Harrison suffered a season-ending knee injury against Penn State on Sept. 27.