birdfeed vs mustard seed

birdfeed

noun
  • Food intended for birds, often a mixture of various seeds. 

mustard seed

noun
  • A small, round seed of the mustard plant. 

  • A small amount. 

  • Small lead shot, usually of size No. 12, used for shooting birds and other animals at close range. 

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