It depends on your definition of "natural" or what your consumers perceive to be natural.

• "Natural" based on raw materials of the package (no petrochemical-based raw materials; raw materials are only plant- or mineral-based)
• "Natural" based on feedstocks used to make the package, i.e., no petrochemical feedstocks (only plant-based like coconut oil)
• There are other environmental considerations -- the package supply chain itself, transportation/shipping methods, distance shipped to destination, percent recycled or percent post-consumer content, percent that is recyclable or can be reused

I am not in Packaging, but to me a 100% natural package would be one that is also fully sustainable and came from renewable sources such as bamboo or wood. Corn would also be a good option for plastic packaging (there are some polymers such as PLA available commercially).