Naturally occuring plumage patterns?
Do you mean in wild Jungle Fowl?
In Red Jungle Fowl the only natural color is BB Red (the females are partridge or wheaten). Some believe domestic fowl were bred from Red, Green and Grey Jungle fowl, however, and the other two species have patterns that almost look like lacing and barring, which could have introduced the genetics.
Most genetics seen today in colors is either a gene that has been mutated or deleted to change an already existing color. This includes white (lack of color), red (lack of any color but red), blue (a dilute), and others.
Natural shapes are thin like leghorns, small (but not bantam sized), no feathering on the legs or extra toes, a single comb, and no extra toes or spurs.
I hope this explains some. I'm no expert, but I have been studying genetics for fun so this is what I have learned.