The Collaborative International Dictionary of English v.0.48:

Grassy \Grass"y\a.
   1. Covered with grass; abounding with grass; as, a grassy
      lawn. --Spenser.
      [1913 Webster]

   2. Resembling grass; green.
      [1913 Webster]

WordNet (r) 3.0 (2006):

grassy
    adj 1: abounding in grass [ant: grassless]

Moby Thesaurus II by Grady Ward, 1.0:

55 Moby Thesaurus words for "grassy":
   aestival, beryl-green, berylline, blue-green, bluish-green,
   caespitose, chartreuse, chloranemic, chlorine, chlorotic, citrine,
   citrinous, emerald, foliaged, glaucescent, glaucous,
   glaucous-green, graminaceous, grasslike, green, green as grass,
   green-blue, greenish, greenish-blue, greenish-yellow, greensick,
   holly, ivy, ivy-green, leafy, leaved, meadowy, moss-covered,
   moss-grown, mossy, olivaceous, olive, olive-green, porraceous,
   smaragdine, springlike, summerlike, summery, swardy, tufted,
   turflike, turfy, verdant, verdured, verdurous, vernal, vernant,
   vert, virescent, yellowish-green