This is the most well-known tongue twister in the English language…
Peter Piper picked a peck of pickled peppers;
A peck of pickled peppers Peter Piper picked;
If Peter Piper picked a peck of pickled peppers,
Where's the peck of pickled peppers Peter Piper picked?
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?
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).