The Collaborative International Dictionary of English v.0.48:

Butter and eggs \Butter and eggs\, butter-and-eggs
\butter-and-eggs\n.(Bot.),
   a name given to several perennial plants having showy flowers
   of two shades of yellow, or of yellow and orange, such as
   Narcissus incomparabilis in Europe, and the toadflax
   (Linaria vulgaris) in the United States; the latter is a
   naturalized weed in North America.

   Syn: toadflax, wild snapdragon, devil's flax, Linaria
        vulgaris.
        [1913 Webster + WordNet 1.5]

WordNet (r) 3.0 (2006):

butter-and-eggs
    n 1: common European perennial having showy yellow and orange
         flowers; a naturalized weed in North America [syn:
         toadflax, butter-and-eggs, wild snapdragon, devil's
         flax, Linaria vulgaris]