two cents vs two cents' worth

two cents

noun
  • A nearly worthless amount, alluding to placing a copper penny on each of the eyelids of a pauper's or slave's body before burial. 

  • One's opinion or thoughts. 

two cents' worth

noun
  • Synonym of two pennies' worth. 

How often have the words two cents and two cents' worth occurred in a corpus of books? (source: Google Ngram Viewer )