When creating my icons I have run into the problem of the pattern being too distracting over the actually icon.
You will also notice I have crossed out iteration number five on the matrix. I have had trouble iterating these icons. With each different icon, I created a concept with the environment of the actual object. (Feather; bird, canoe; water, tomahawk;trees, tree; clouds, teepee; other teepees, headdress; head, fire; smoke/people dancing around, crane; cat tails/reeds, moccasins; path, necklace; hand/neck). I kept questioning wither the background shape to the icon was overpowering the importance and hierarchy of the the icon, itself. Sometimes, a good idea isn't always problematic.
Also, I have created an overlay and basis for the icons with a pattern. The pattern is simply composed of lines and squares. This will make the icons, that use the pattern, more cohesive.