The Terps will open their first 20-game Big Ten slate with December matchups against Penn State and Purdue.
The three-star recruit out of Washington, D.C., had previously planned to spend a post-grad year at prep school.
Maryland's 10-day trip to Italy includes three scrimmages and additional practice time.
Herard would not have been eligible until midseason after transferring from Mississippi State in January.
Kevin Huerter, a 6-foot-7 sharpshooter, left Maryland after two seasons and is now officially a pro after the Hawks drafted him 19th overall.
Clark leaves Maryland to join a family business after seven years with Maryland. Matt Brady, a two-time Division I head coach, was promoted in his place.
The 6-foot-7 shooter is widely considered a first-round pick after a strong showing at the draft combine.
The big man's return gives the Terrapins a frontcourt anchor heading into next season.
Bruno Fernando is testing the NBA Draft waters and has until May 30 to decide whether he'll return to College Park.
The sophomore, second on the team in scoring last year, is the third Terrapins player this offseason to at least explore his professional options.