lambkin vs sweet pea

lambkin

noun
  • A term of endearment. 

  • A young lamb, a very young sheep. 

sweet pea

noun
  • A term of endearment for something sweet or lovely; a child or an intimate partner, for example. 

  • A flowering plant, Lathyrus odoratus, grown for its bright colours and sweet fragrance. 

How often have the words lambkin and sweet pea occurred in a corpus of books? (source: Google Ngram Viewer )