"Hot Cross Buns" is a traditional Nursery Rhyme. Hot Cross Buns are a spicy bun with a little cross shape on top which are traditionally sold at Easter time, but tasty at any time of year (if you can find them). It's great the way a street seller's cry has become a rhyme for children, and the patter of salesmen hasn't changed much over the years. The PDF sheet music, Midi and Mp3 files for the standard melody can be downloaded using the links in the left-hand menu.
The image below is the first page of the sheet music, and here you can download the full sheet music for Hot Cross Buns for piano in PDF format.