"Frere Jacques" is a traditional nursery rhyme or children's song of French origin. There are various English translations of the rhyme such as "Brother James" or "Brother Joseph", but curiously the rhyme seems to be most often sung in French in the UK. Perhaps this is simple because it is hard to get a good translation which fits the melody so well. The story is about a monk called "Frere Jacques" or "Brother James" who should be getting up because the morning bells are ringing. The PDF sheet music, Midi and Mp3 files for this the standard melody can be downloaded using the links in the left-hand menu.
However the song is often sung in the form of a Round and here is the Round Version of Frere Jacques.
The image below is the first page of the sheet music, and here you can download the full sheet music for Frere Jacques for piano in PDF format.