This is the version I sing to my daughter:

Hush now baby don't say a word
Momma's gonna buy you a mockingbird
And if that mockingbird don't sing
Momma's gonna buy you a diamond ring
And if that diamond ring turns to brass
Momma's gonna buy you a looking glass
And if that looking glass gets broke
Momma's gonna buy you a billy goat
And if that billy goat runs away
Momma's gonna start again the very next day.