Natural Products and Child health interest in the mobil apps
There are indeed a number of health and nutrition apps for children. There also are many others that, not being tailored specifically for children, are simple enough for kids to use.
However, in order to answer the question, it would be interesting to know the age ranges your are targeting as well as what exactly are you expecting to achieve,
There are several apps on natural/organic food. For example, BuzzFeed has listed 21 of them https://www.buzzfeed.com/michelleno/apps-that-make-it-easy-to-eat-healthy?utm_term=.dh9egEX9E#.pseWEawRa (Disclaimer: I do not endorse any of these apps).
If the question pertains to mobile app for use of natural products in a medical context for treatment of specific diseases such apps do exist in both iOS (for e.g. Natural Medicines by Therapeutic Research Center) as well as Android (for e.g. Home Remedies+ : Natural Cures). (Disclaimer: I do not endorse any of these apps).
There are several such mobile apps available but it depends on what actually you are looking for and which age group. Some of the mobile apps are:
Recipes For Kids
14 Baby Food Age 6 Months
Health and Nutrition Guide
Baby Solid Food
Kids Healthy Meal Recipes
Baby Food Recipe
Healthy Nutrition Guide Babies
Healthy Eater - Baby's Diet
Nutrition For Kids
Baby & Kids Healthy Nutrition Food Recipes