try cross breedin them with the giant head strains yourself . Native seeds seach has a white seeded sunflower , Italian white is small but has almost white petals , sonja is orange petalled , chianti is wine ( dark red ) there are red petaled and purple petaled strains a combination brown and yelllow strain there is the tedddy bear stain with the dandylion like bloom and combination strains like "music box" and "jokers" strains .there is also the giant seed strains like "titan " I have seen seeds over 2 inches long and others very wide in the health food store ( they must have been roasted because they would not grow) . Check the hybrids forum . There are also sunflowers grow for there height 25 feet or so . see what you can do.

farm, I think he is asking about giants.
phyl, I haven't seen one that is other than yellow. However, it's possible to have giants of any color by cross them with smaller sunflower of different color and keep just the biggest and tallest each year. Eventually you will get white, red, orange, etc. giants sunflower.
That's a fun project but it may take 10-15 year to have the color stablized (my guess).