buttonmould

from The Collaborative International Dictionary of English v.0.48

Buttonmold \But"ton*mold`\, n.
   A disk of bone, wood, or other material, which is made into a
   button by covering it with cloth. [Written also
   {buttonmould}.]
   [1913 Webster]

   {Fossil buttonmolds}, joints of encrinites. See {Encrinite}.
      [1913 Webster]