The rhyme behind the playground seesaw chant, though it comes with a strange little detail: Margery Daw has sold her bed and is sleeping on straw. The bounce of the words does most of the work.
From Mother Goose / Nursery Rhymes (traditional). See the whole collection.
See-saw, Margery Daw,
Sold her bed and lay upon straw.
Public domain. Text from The Real Mother Goose (Blanche Fisher Wright, 1916), via Project Gutenberg. View the source edition