A daisy is a cheerful white flower with yellow in the center. Drive through the countryside in mid-summer and you can often see whole fields full of daisies.
Daisies grow wild in many places, and they're also cultivated in gardens as a perennial, a plant that returns year after year. One invasive variation is called a "lawn daisy" because it quickly and easily takes over grassy lawns and is notoriously hard to mow down. The word daisy comes from day's eye, an informal name that arose from the flower's habit of closing its petals when the sun goes down at the end of the day.