According to the nursery rhyme, Peter Piper picked a peck of pickled peppers. A peck is a unit of measurement of dry volume. One peck is equal to 8 dry quarts or 16 dry pints, so Peter picked 8 quarts of peppers.

"Peter Piper" is a well-known Mother Goose nursery rhyme and tongue twister. "Peter Piper" was first published in 1813 as part of the book "Peter Piper's Practical Principles of Plain and Perfect Pronunciation" by John Harris. The entire tongue twister is "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?"