Berries - strawberries, raspberries, and blackberries - are a food that should never be eaten past the expiration date. Visually inspect berries, and once they start to break down, discard them. Berries can contain a microscopic parasite known as Cyclospora, which can make you and your child very sick. I have returned many berries to the grocery due to break down and mold, and they are always happy to refund my money. Better safe than sorry.