kingcup vs mayweed

kingcup

noun
  • Any of various species of buttercup, or the marsh marigold, Caltha palustris. 

mayweed

noun
  • Plants of the genera Matricaria and Tripleurospermum. 

  • corn chamomile, field chamomile, Anthemis arvensis. 

  • A mayflower. 

  • stinking chamomile, Anthemis cotula. 

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