As a freshman, Mahaffey averaged 9.4 minutes, 2.8 points, and 1.7 rebounds per game, while shooting at a 56.9% clip from the field.
Imes commitment to Notre Dame finalizes an exodus of high school signees from Penn State.
The organization has raised over $3.6 million from its founding in 1995.
Toby Ezeonu returned in the third set after sustaining an injury during the conference semifinals.
O'Boyle is the sixth transfer to commit to Penn State since head coach Mike Rhoades took over the program.
Booth, the son of Penn State hoops legend Calvin Booth, boasted a four-star status as a recruit and will take his talents to South Bend.