The word ricegrasses is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 16
Highest Scoring Words With Friends™ Play In The Letters ricegrasses
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Seven Letter Word Alert: (21 words)
careers, carries, cerises, crasser, creaser, creases, cresses, erasers, gassers, gassier, grasses, greaser, greases, raisers, rearise, regears, regress, sassier, scarers, scarier, sierras