On today's date, 1858, Hymen Lipman was granted a patent for attaching a piece of rubber to the end of a pencil. While it was certainly a stroke of genius, the courts didn't think it to be as groundbreaking as one might think. From Smithsonian:
Unfortunately for Lipman, the patent would later be revoked, when the U.S. Supreme Court rules in 1875 that a pencil with an eraser is just a pencil with an eraser and not a new invention.
For more than you ever wanted to know about the history of the pencil, don't miss Henry Petroski's book The Pencil: A History of Design and Circumstances.