"Pearl" was the name of blues singer Janis Joplin's last album (which was released shortly after her death). I read that the reason it's called that was because Pearl was a nickname that Janis Joplin gave herself (and that was used by some people she knew).
Minnie Pearl: Stage name for Sarah Ophelia Colley Cannon (October 25, 1912 – March 4, 1996), who was a member of the Grand Ole Opry from 1940 until her death.
Pearl Forrester from Mystery Science Theater 3000. Originally she was just a supporting character and mother of the show's main villain Clayton Forrester. In the Sci-Fi version of the series, she became the main villain.