If "ifs" and "ands"
Were pots and pans,
There would be no need for tinkers*!
*A tinker was someone who mended metal pots and pans!
W. Gannon wrote that this rhyme is: "A laconic reply to a person who indulges much in supposition." Gannon edited Mother Goose Nursery Rhymes, Tales and Jingles (1902).
Thanks and Acknowledgements
This rhyme can be found in Children's Literature, A Textbook of Sources for Teachers and Teacher-Training Classes (1920) by Charles Madison Curry and Erle Elsworth Clippinger and also in Gannon's book from 1902.