Picture books children can sing immediately
Traditional-song books have a huge advantage: children can often join in from the very first read because the melody is already familiar.
Down By the Bay
Five Little Ducks
Spider on the Floor
The Wheels on the Bus
I Know an Old Lady Who Swallowed a Fly
Mary Had a Little Lamb
Miss Mary Mack
Skip to My Lou
These titles are especially useful for rhyme prediction, group participation, and connecting what children hear to what they see on the page.