Chocolate Frogs are a 'Croakoa' made food product which is popular among Witches and Wizards. The box containing the chocolate frog also contains collectable Famous Witch and Wizard cards which you can collect and swap. The frogs have the ability to act like frogs though 'only have one good jump in them'.
 Philosopher's Stone
In 1992 after his fight with Professor Quirinus Quirrell and Lord Voldemort, Harry Potter was sent to the Hospital Wing. Whilst there, Harry receives several gifts and well wishers including several chocolate frogs. Unfortunately for Harry, Ron Weasley had eaten them before Harry woke.