Singular
Mary Jane

Plural
Mary Janes

 
Mary Jane-style shoes
  1. (uncountable) Mary Jane is a female double given name.
    My daughter is named Mary Jane.
  2. (uncountable); (slang) Mary Jane is marijuana.
    I just got arrested for selling Mary Jane.
  3. (countable) A Mary Jane is a kind of shoe.
    I think Mary Janes will look good with that dress.