Think frogs, turtles, fish, beachy colors, mixing in blues, beiges with the cream would be nice. If you wanted to keep to strictly green/cream, you could try some shades of green and do something like a bargello or trip around the world.
Go to Google images and search for green baby quilts for more inspiration:
https://www.google.com/search?q=gree...HouK9QTqmICgBQ