Lunaria annua vs silver dollar

Lunaria annua

silver dollar

noun
  • A dollar coin, whether made from silver or not. 

  • A small pancake. 

  • Several species of tropical freshwater fish of the genus Metynnis, of the family Characidae or Serrasalmidae, of which Metynnis argenteus is one; popular for aquariums; so named from their shape and flashing silver color. 

How often have the words Lunaria annua and silver dollar occurred in a corpus of books? (source: Google Ngram Viewer )