The Collaborative International Dictionary of English v.0.48:

Campion \Cam"pi*on\, n. [Prob. fr. L. campus field.] (Bot.)
   A plant of the Pink family (Cucubalus bacciferus), bearing
   berries regarded as poisonous.
   [1913 Webster]

   Bladder campion, a plant of the Pink family (Cucubalus
      Behen or Silene inflata), having a much inflated calyx.
      See Behen.

   Rose campion, a garden plant (Lychnis coronaria) with
      handsome crimson flowers.
      [1913 Webster]

U.S. Gazetteer (1990):

Campion, CO (CDP, FIPS 11590)
  Location: 40.34468 N, 105.09498 W
  Population (1990): 1692 (582 housing units)
  Area: 9.8 sq km (land), 0.1 sq km (water)