Cryptogram Nursery Rhyme

The hint for the 10th letter in the cryptogram puzzle can be deciphered through this Mother Goose nursery rhyme…

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?


Do you know which letter I’m talking about??
🙂
~TSGal