This is the most well-known tongue twister in the English language…

Peter Piper Picked a Peck of Pickled Peppers - English Children's Songs - England - Mama Lisa's World: Children's Songs and Rhymes from Around the World  - Intro Image

Notes

A peck is a measurement used for dried goods. It's equal to 2 gallons.

Here's a slightly different version from The Little Mother Goose (1912), illustrated by Jessie Willcox Smith:

[To be read rapidly.]

Peter Piper picked a peck
Of pickled pepper;
A peck of pickled pepper
Peter Piper picked;
If Peter Piper picked a peck
Of pickled pepper,
Where's the peck of pickled pepper
Peter Piper picked?

Peter Piper Picked a Peck of Pickled Peppers - English Children's Songs - England - Mama Lisa's World: Children's Songs and Rhymes from Around the World  - Comment After Song Image

Comments

Curry and Clippinger wrote: "Halliwell suggests that 'off a pewter plate' is sometimes added at the end of each line. This rhyme is famous as a 'tongue twister,' or enunciation exercise." Halliwell was a well-known editor of nursery rhyme books from the 19th century.

Thanks and Acknowledgements

This tongue twister 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. The illustration is from The Nursery Rhyme Book, edited by Andrew Lang and illustrated by L. Leslie Brooke (1897).