In most games featuring Yoshis, Yoshi Eggs are involved. Yoshis are known for being capable of laying eggs at will, sometimes with Yoshis or items inside.
The download file contains 7 different egg colors to choose from.
Design by Brandon and Paperbuff.
UPDATE: (02/11/2009) The PDF files have been updated to contain all 7 colors both for the lined and unlined versions. Just print the page with the color you want.