Corelle does have a third pattern Holly Days (1984). The two main differences are, it has black viens in the leaves and the green is a lighter color.
Personally, I'm going to try to only collect the dishes with the white veins so everything feels more like a set.
CorelleCorner.com is a good place to find info on patterns and this pic is courtesy of their site,
and there's a great article on EBAY with more holiday Corelle information HERE.
I'm thrilled to finally have some of these fun seasonal dishes, Merry Christmas: to me-from me!
Have a Happy Holly Day:@)