Eggshells are either blue (dominant) or white (recessive). Ad to that that a wash of brown pigment can be added to the outer surface of the shell, and you will get green eggs is the shell is blue or brown if it is white. There are many genes that go into determining the colour of the wash (some that add pigment, some that remove it), so it can be difficult to determine what you might get, especially with a mix of white, brown and blue egg layers.
The leghorns and rhode islands have white eggshells; the easter eggers may have blue eggshells (without seeing their eggs, it is hard to say as they are essentially a mutt that had a blue egg laying ancestor).
The blue egg gene is linked to the pea comb, so any chicks that have a pea comb are likely to lay a blue or green egg, and chicks with single combs are likely to lay a white or brown egg, but that is not a 100% guarantee in either case. More like 97%.