In their 'The Singing Island', Ewan MacColl and Peggy Seeger gave the following as used by children in Edinburgh as a 'frightening' rhyme in the early 20th century:

There was an old lady all skin and bone
She went to the churchyard all alone
And when she came to the churchyard door
Behold a dead man on the floor
The worms and snails through him did creep
Then asked the lady while sore she did weep
Will I be this way when I die?
And then the dead man answered: Aye!

They commented also that American children had a more graphic version which ran:

The worms crawl in, the worms crawl out
The worms play pinochle on your snout