The Collaborative International Dictionary of English v.0.48:

Haycock \Hay"cock`\ (h[=a]"k[o^]k`), n.
   A conical pile or heap of hay in the field.
   [1913 Webster]

         The tanned haycock in the mead.          --Milton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

haycock
    n 1: a small cone-shaped pile of hay that has been left in the
         field until it is dry enough to carry to the hayrick