penny bun vs porcini

penny bun

noun
  • An edible mushroom (Boletus edulis). 

  • A small bun that sells for a penny. 

porcini

noun
  • An edible mushroom (Boletus edulis), prized for its flavor. 

How often have the words penny bun and porcini occurred in a corpus of books? (source: Google Ngram Viewer )