The Collaborative International Dictionary of English v.0.48:

Rie \Rie\, n.
   See Rye. [Obs.] --Holland.
   [1913 Webster]

   Rie grass. (Bot.)
   (a) A kind of wild barley (Hordeum pratense). --Dr. Prior.
   (b) Ray grass. --Dr. Prior.
       [1913 Webster]

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

RIE
       Reactive Ion Etching (IC)