Feather (Mario's Time Machine)
From the Super Mario Wiki
The Feather is an item in the SNES and PC releases of Mario's Time Machine. It is a prop that has been used for many costumes in William Shakespeare's plays. Richard Burbage mentions to the time-traveling Mario that he needs a feather to complete his costume, and after Mario mentions this to Anne Hathaway, she gives him the Feather while describing its history to him. Mario then brings the Feather back to Richard, who promptly begins to quote a character from the play he is about to act in, Shakespeare's Hamlet: "This above all: to thine own self be true / and it must follow, as the night the day, / thou canst not then be false to any man," (1.3.79-81) which is said by Polonius to his son Laertes as he prepares to go to college.