Apple

Apples were a common fruit found on Earth. The Doctor, in his fourth incarnation claimed that he dropped apples on Isaac Newton's head. (DW: The Pirate Planet) In his seventh incarnation whilst visiting the Worldsphere the Doctor met a parachute that designed apple trees in its spare time. (NA: The Also People) Following his regeneration into his eleventh self the Doctor thought he wanted an apple but didn't like it. Amy Pond disliked apples when she was young, until her mother began carving happy faces into them. She gave an apple with a carved happy face on it to the Doctor when he first met her. Not long after (for the Doctor) but 12 years later (for Amy), the Doctor produced it in order to finally convince the older Amy that he was the same man she met as a child. (DW: The Eleventh Hour)