maverick (n.)
1867, "calf or yearling found without an owner's brand," a word from the great cattle ranches of the American West, so called for Samuel A. Maverick (1803-1870), Texas cattle owner who was notoriously negligent in branding his calves.
All neat stock found running at large in this State, without a mother, and upon which there is neither mark nor brand, shall be deemed a maverick, and shall be sold to the highest bidder for cash, at such time and place, and under such rules and regulations, as the round-up commissioners of the district shall prescribe. [act to amend the General Statutes of the State of Colorado, approved April 8, 1885]
The family name is an old one in Boston, and a different Samuel Maverick was killed in the Boston Massacre.
https://www.etymonline.com/word/maverick