White cake that I can "dye" with berries.

just came across this browsing google images for something else, had to share! ;) http://secretlifeofachefswife.com/anthologie/desserts/the-coolest-fourth-of-july-cake-ive-ever-seen

I saw this cake today on a blog I follow, the layers are not completely colored but it looks beautiful. http://www.creative-culinary.com/july-4th-red-white-and-blue-patriotic-cake/#more-19868

Thanks for all these suggestions!

i bought a natural food coloring set by india tree once, but i don't know that i ever baked with it... i think it was from dean & deluca, but i imagine something like that is now sold more widely than it used to be. perhaps you could consider making a raspberry (or pomegranate or strawberry) compote and adding in whole blueberries? that combination would look great against the backdrop of a pristine white cake with a delicious butter cream frosting. plus then you wouldn't have to fret about how the inside of the cake was going to turn out (which you wouldn't know until you cut it open, probably!). hope it works out!

Check out this link which describes how to make natural food coloring and how to add it to your cake
http://www.inhabitots.com/diy-organic-rainbow-cake-without-toxic-chemical-food-colors/

Yes, but...
in my experience and observations, berries added to white cake come out either grey-ish purple or puce in color. They aren't the same vibrant happy colors prior to baking. In fact, they can look downright frightening. The natural colors aren't heat-stable. You might have better results with beets.

What about red beets for dying the white cake? Or raspberry compote with the seeds strained out?

I've always wanted to make this:
http://food52.com/blog/4574-nigel-slater-s-extremely-moist-chocolate-beet-cake
Perhaps you could leave out the dark chocolate or put white chocolate instead?
http://www.marthastewart.com/355507/vanilla-bean-buttercream