The word stonecress 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: 14
Highest Scoring Words With Friends™ Play In The Letters stonecress
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Seven Letter Word Alert: (31 words)
cenotes, censers, censors, centers, centres, cornets, corsets, cresses, cresset, crosses, encores, escorts, estrone, necrose, nesters, octenes, renests, resects, resents, scenter, screens, secerns, secrets, sectors, sensors, stenose, stereos, stoners, tensors, tossers, tresses