A punnet is a small container for the gathering and sale of fruit and vegetables, typically small berries. The word is largely confined to Commonwealth countries and is of uncertain origin, but is thought to be a diminutive of "pun", a British dialect word for pound, from the days in which such containers were used as a unit of measurement.
Punnets were originally a round wood chip basket but typically are now rectangular and made of plastic; increasingly moulded pulp and corrugated cardboard are being used as they are perceived to be more sustainable materials. Decorative punnets are often made of felt and seen in flower and craft arrangements.
- Shorter OED