If you are looking for songs in the Irish language, there is a truly excellent CD that has the music and written lyrics for several children's songs. It is called "A Stór 'is A Stóirín" by Pádraigín Ní Uallachain and Garry Ó Bríain. It also includes written lyrics and translations.

There is also another CD which I have not heard, also by O Briain and Ni Uallachain, called "When I was Young - Children's Songs from Ireland." The publisher is Gael Linn.