The Collaborative International Dictionary of English v.0.48:

Mow \Mow\, v. [pres. sing. Mow, pl. Mowe, Mowen, Moun.]
   [AS. magan. See May, v.]
   May; can. "Thou mow now escapen." [Obs.] --Chaucer.
   [1913 Webster]

         Our walles mowe not make hem resistence. --Chaucer.
   [1913 Webster]