The Collaborative International Dictionary of English v.0.48:

Raff \Raff\, n.
   1. A promiscuous heap; a jumble; a large quantity; lumber;
      refuse. "A raff of errors." --Barrow.
      [1913 Webster]

   2. The sweepings of society; the rabble; the mob; -- chiefly
      used in the compound or duplicate, riffraff.
      [1913 Webster]

   3. A low fellow; a churl.
      [1913 Webster]

   Raff merchant, a dealer in lumber and odd refuse. [Prov.
      Eng.]
      [1913 Webster]