I chose a piece of paper representing a letter that Artemidorus wrote to warn Caesar of the conspirator's plan but never got a chance to. What gave me this idea was found  in ACT 3, Scene 1, lines 1-11. In this section Artemidorus writes a letter for Caesar to read but Decius suspects that that man knows the plan and steps in front to offer Caesar a request from someone else. Before Artemidorus can tell Caesar of the plot, Publius pushes him aside and they all walk past him. To me this show that the conspirators were careless to the point were anyone can know their plot.