Little Jack Horner

Little Jack Horner,
Sat in a corner,
Eating his Christmas pie.
He put in his thumb,
And pulled out a plum,
And said 'what a good boy am I.'
 

This rhyme was first published in 1725

It is thought to refer to a Jack Horner who lived at the time of the dissolution of the monasteries by Henry VIII in 1536. Jack Horner served the abbot of Glastonbury and was instructed to take a huge Christmas pie to the King. Inside the pie were the deeds to the Manor of Mells in Somerset. The plum almost certainly refers to those deeds.