A few months ago I was home visiting my parents and we had a lunch with a few other Maharashtrians. The conversation turned towards food, and in particular ingredients that are important for making authentic garam masala. Garam masalas vary widely by region in India, and the two ingredients in question were dagadful and nag kesar. I had never really heard of these spices so I did a bit of research to learn more.
Dagadful (Parmelia perlata) is a lichen, not to be confused with the stone flower Didymocarpus pedicellatus, which is a plant that grows on rocks and is called charela in Hindi, I believe. The confusing thing is that both plants are used for herbal remedies, but the former is used for culinary purposes.
If you search for “nag kesar” you may find Mesua ferrea, a hardwood tree that grows in India and surrounds. That’s not where the spice comes from, however. This sparked the most debate at lunch, but I think I’ve figured out that the spice is the bud of a different tree, Mammea longifolia. Both Mesua and Mammea are in the family Calophyllaceae, which probably led to the name clash.
An Ergodic Walk 
Wow, they look very interesting! Can you get them in the US?
Well, at some grocery stores yes. Kalyustan’s in NYC probably has them, but I am not sure where you can get them in SD…
Dagad phool or Pathar phool can allegedly be ordered from the Amazon web site (seller and shipper from Kochi, India), but when we ordered it, we got what looked like rock salt. Dagad and Pathar, or Patthar, means rock or stone in Marathi and Hindi respectively, and so perhaps the shipping clerk reached into the next bin in their warehouse and sent us the wrong product. The shipper did not even bother responding when we complained that they had shipped the wrong product, but Amazon refunded our money. My sister found us some in an Indian grocery store in Detroit, and we had previously found it in an Indian grocery store on Devon Street in Chicago.