Originally Posted by feline fanatic

The name of that quilt block is Anvil.

Edited to add, the anvil block has several variations. You can find many free quilt blocks on quilter's cache and one of her variations would work but I would be inclined to piece it with less seams
http://www.quilterscache.com/T/TheAnvilBlock.html


She has several southwestern looking blocks, like
http://www.quilterscache.com/B/BrotherBearBlock.html

I modified this one to a 12" block quite easily (and also cut out a bunch of seams)
http://www.quilterscache.com/S/SquashBlossomBlock.html

This one has kind of a Southwest feel
http://www.quilterscache.com/M/MontanaMtnMazeBlock.html

This one can also be made to look quite southwestern depending on color/fabric placement
http://www.quilterscache.com/D/Diamond4PatchBlock.html



Also google images of navajo weaving to get loads of inspiration and ideas. many of the more simple weavings can be easily converted to quilt block units.