"Justin Garrett did not pass a course that he needed to pass, and therefore he will not be with us," Fulmer said. "He will not report."
Yancey is a 5-8, 200-pound senior running back who rushed 13 times for 42 yards last fall, caught two passes for 14 yards and returned two kickoffs for 40 yards.
Frogg is a 6-4, 300-pound junior who finished spring practice listed No. 1 on the depth chart at center. He also can play guard.
Greene is a 6-0, 200-pound junior safety who ranked second on the team last fall with five special-teams tackles.
Fulmer said it was "very much a positive" to reward four players who "have been great Volunteers for us."
The head man said a couple more walk-ons could receive aid, depending on what happens with Williams and Raines regarding the NCAA Clearinghouse.
Fulmer conceded that these Clearinghouse matters are "frustrating, in that it seems like it takes so long."