The Collaborative International Dictionary of English v.0.48:

Bedstraw \Bed"straw`\, n.
   1. Straw put into a bed. --Bacon.
      [1913 Webster]

   2. (Bot.) A genus of slender herbs, usually with square
      stems, whorled leaves, and small white flowers.
      [1913 Webster]

   Our Lady's bedstraw, which has yellow flowers, is Galium
      verum.

   White bedstraw is Galium mollugo.
      [1913 Webster]

WordNet (r) 3.0 (2006):

white bedstraw
    n 1: Eurasian herb with ample panicles of small white flowers;
         naturalized in North America [syn: wild madder, white
         madder, white bedstraw, infant's-breath, false baby's
         breath, Galium mollugo]