coffin vs potter's field

coffin

noun
  • A rectangular closed box in which the body of a dead person is placed for burial. 

  • A storage container for nuclear waste. 

  • The eighth Lenormand card. 

  • The hollow crust or hoof of a horse's foot, below the coronet, in which is the coffin bone. 

verb
  • To place in a coffin. 

potter's field

noun
  • A public place where strangers, paupers, and criminals are buried. 

How often have the words coffin and potter's field occurred in a corpus of books? (source: Google Ngram Viewer )