GreenMedInfo.com is a great place to research the science and healing benefits about calendula plants, especially the anti-cancer benefits found in some herbs and on PUBMED you can also research chamomile! Check it out! These are the kind of side effects I can live with! There are many more to research! Honestly the best place to investigate the medicinal properties found in plants from nature would be with the former USDA botanist, Dr James A DUKE and his data base full of 30 years of research!
I buy and learn about most organic herbs and flowers I cannot grow, at: MountainRoseHerbs.com