The Collaborative International Dictionary of English v.0.48:

Spadefoot \Spade"foot`\ (sp[=a]d"f[oo^]t`), n. (Zool.)
   Any species of burrowing toads of the genus Scaphiopus,
   esp. Scaphiopus Holbrookii, of the Eastern United States;
   -- called also spade toad.
   [1913 Webster]