Here's all the major leaguers I could find who appeared in an NCAA basketball tournament.

(Player, School, year of tournament appearance)

» Sam Mele, NYU, 43
» Don Grate, Okla. St., 44-45
» Robin Roberts, Mich. St., 47
» Tom Hamilton, Texas, 47
» Sammy White, U. of Wash., 48
» Dave Sisler, Princeton, 52
» Rick Herrscher, SMU, 56
» Steve Hamilton, Morehead St., 56-57
» Earl Robinson, Cal, 58
» Jerry Adair, Okla. St.,58
» Rollie Sheldon, UConn, 60
» Paul Popovich, WVU, 60
» Dave DeBusschere, Detroit, 62
» Jerry Martin, Furman, 71
» Dave Winfield, Minn, 72
» Tim Stoddard, NC St., 74
» Danny Ainge, BYU, 81
» Ben McDonald, LSU, 87
» Kenny Lofton, Ariz., 88
» Lyle Mouton, LSU, 89
» Terrell Lowery, Loyola Marymount, 90
» Ryan Minor, Okla., 96