The Collaborative International Dictionary of English v.0.48:

Scalloped \Scal"loped\, a.
   1. Furnished with a scallop; made or done with or in a
      scallop.
      [1913 Webster]

   2. Having the edge or border cut or marked with segments of
      circles. See Scallop, n., 2.
      [1913 Webster]

   3. (Cookery) Baked in a scallop; cooked with crumbs.
      [1913 Webster]

   Scalloped oysters (Cookery), opened oysters baked in a deep
      dish with alternate layers of bread or cracker crumbs,
      seasoned with pepper, nutmeg, and butter. This was at
      first done in scallop shells.
      [1913 Webster]