Daisy Pennifold was a witch who lived in the 18th century. Shortly after the change in colour of the Quaffle, Daisy came up with the idea of enchanting the ball so that it fell to the ground slower than it should. This change allowed the Chasers to retrieve the ball while it was still in mid-air, rather than having to collect it from the ground. These Quaffles became known as the Pennifold Quaffle, and are still used today.
The name "Daisy" comes simply from the English word for the white flower, ultimately derived from Old English dægeseage meaning "day eye". It was first used as a given name in the 19th century, at the same time many other plant and flower names were coined.