After a four month investigation, ESPN's "Outside the Lines" reported Sunday that the Trojan basketball star received cash and gifts while at USC.
Mayo announced in April that he had hired an agent and was leaving USC after just one season.
Louis Johnson, a former Mayo associate, provided "Outside the Lines" with receipts and invoices for items including a flat screen television, clothes, meals, and airline tickets.
According to Johnson, Mayo received the items from Rodney Guillory, a Los Angeles event promoter with ties to northern California sports agency firm Bill Duffy and Associates.
Johnson said up to $30,000 was involved in the transactions.
"The NCAA and the Pac-10 reviewed O.J. Mayo's amateur status before and during his enrollment at USC, and did not identify any amateurism violations. Mayo and USC cooperated in these investigations," USC said in a statement.