The Collaborative International Dictionary of English v.0.48:

Spelk \Spelk\, n. [AS. spelc, spilc, a little rod by which a
   thing is kept straight, a splint for binding up broken bones,
   akin to Icel. spelkur, pl., a splint. Cf. Spell a
   splinter.]
   A small stick or rod used as a spike in thatching; a
   splinter. [Prov. Eng.] --Grose.
   [1913 Webster]