Wiktionary
n. (context espionage English) items in a spy's pocket (ex. ticket stubs, coins) to make their cover seem more authentic
Wikipedia
Pocket litter is material, including notes scribbled on scraps of paper, that accumulates in an individual's pockets. It can include identity cards, transportation tickets, personal photographs, computer files and similar material.
Counter-terrorism analysts report that the analysis of pocket litter can be an important tool for confirming or refuting suspects' accounts of themselves.
The term was used as early as 1973, by Watergate conspirator E. Howard Hunt.
The Combatting Terrorism Center celebrated the first anniversary of the killing of Osama bin Laden by releasing documents seized from Osama bin Laden's Abbottabad home. The Associated Press reported that SEAL Team 6 had been specially trained to search for documents and pocket litter "that might produce leads to other terrorists."
Usage examples of "pocket litter".
He rummaged around in his outer coat, sorting through his pocket litter: a cigarette butt, a sliver of soap wrapped in a soiled handkerchief that served as a washcloth, part of a day-old pastrami sandwich and a piece of an onion bagel found in a garbage can behind a deli.
She put on her business suit over the weapons and assembled the ID package and pocket litter that identified her as an FBI agent from Washington.