wattle and daub

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A building material consisting of interwoven rods and laths or twigs plastered with mud or clay, used especially in the construction of simple dwellings or as an infill between members of a timber-framed wall.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A structure of interwoven branches and twigs plastered with mud, clay or dung, used in the construction of dwellings, especially as infill in a half-timbered wall

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun building material consisting of interwoven rods and twigs covered with clay