What does Tarrance leave in his drawer?

The Firm, by John Grisham, falls into the category of a legal thriller. Wayne Tarrance is the FBI agent assigned to work with the main character, Mitch McDeere, a Harvard law school graduate and a new employee at the Bendini law firm in Memphis, Tennessee. Tarrance initially approaches McDeere in a deli to pass along a warning, that things are not as they seem at the firm. Although unsure how to respond at first, McDeere becomes convinced that Tarrance is telling him the truth and becomes intensely fearful and wary of the people at his new firm. A little digging shows on his part confirms Tarrance's statement that the recent deaths of some of the firm's associates are not accidental. In fact, the deaths were ordered by the firm's leadership. Risking his own life, McDeere eventually agrees to obtain documents that will show evidence of the firm’s illegal activities, in order to allow the FBI to initiate an investigation into the firm.
After a careful rereading of this work, I do not see any reference to items that Tarrance has left in his drawer or desk! In fact, the reader never sees Tarrance’s office or home at all; all meetings between Tarrance and McDeere take place in settings such as buses, restaurants or over the phone.