An egg is an egg is an egg...

After reading the 1957 American Home article, I started thinking about different colors of eggs that would have been available then, and how cool it would be to make a mosaic using only the original colors of the eggshells.

Most commercial egg layers are leghorns, and they lay white eggs. But there are a lot of small farms raising less common breeds, and their eggs are all sorts of colors – blue, green, red, brown – and a lot of these eggs are making their ways to farmers markets, co-ops, etc. These eggs are well worth looking for, because not only are they all sorts of interesting colors, they are often from organically raised, free-range chickens. With urban farming on the rise, I wouldn’t be surprised if there are actually more varieties of eggs available now than in 1957.

Check out Henderson's Handy-Dandy Chicken Chart for a good idea of what’s out there. Granted some of these are pretty rare breeds, but someone in your area may be raising Ameraucanas (blue, green, pink), Marans (chocolate brown), Rhode Islands (brown), or Silkies (cream). Make friends with these folks!
 
Also keep an eye out for other non-chicken eggs - guinea hen and turkey eggs are speckled, for example. Try an image search for a few of these ("Marans eggs", for example) - the variety is impressive.