I really feel like Dumathoin is missing from the list of "nature" deities that should allow druid followers. There are many reasons for this:
1) Dumathoin is the keeper of secrets under the mountain, the lord of the underground. There is nothing lesser about the nature of caverns, tunnels, mushrooms, and algae as compared to the plains, valleys, trees and flowers off the surface. They are both equally natural just shaped differently. So being lord of the spaces under the earth, is being attuned that aspect of the greater natural world.
2) His dogma, demands his followers respect and maintain the natural world. A very druid concept.
www.thievesguild.cc/gods/god?godid=149"Walk the deep and silent ways of Dumatoin. Seek out the hidden gifts of the Keeper of Secrets under the Mountain. That which is hidden is precious, and that which is precious shall stay hidden. Seek to enhance the natural beauty of Dumathoin's gifts and go with, not against, the contours of the deeps. "
3) Dumathoin is also essentially the God of Dwarven subterranean agriculture:
"Priests of Dumathoin always seek to uncover the buried wealth of the earth without marring the beauty of the ways beneath the surface or being overly greedy. They often supervise mining operations and maintain underground safety and security. They work to clean up the rubble of mining, to grow and put in place luminous fungi and edible deep-mosses, and to direct water through the earth to best serve the underlife that includes, of course, dwarves."
en-academic.com/dic.nsf/enwiki/1923568"Dumathoin's clerics dress in brown leather. Their heads are bare, but they wear earth-brown cloaks and robes. They never trim their hair or beards. Their favored weapon is either the warhammer or military pick. They seek to uncover the treasures of the earth without marring the natural beauty of the tunnels and mines and without succumbing to greed. They supervise mines, ensuring they are safe and secure from monsters. They also help with subterranean agriculture. They are morticians and protectors of tombs."
4) Comparing the dogma of say Chauntea, to Dumathoin, they are very similar. Agriculture is the process of shaping the natural world to enhance it toward the needs of the people farming. Druids of Chauntea encourage certain plants and deny others (weeds) in order to best feed those around them. Chauntea preaches to do so with as small an impact on the natural world as possible. Dumathoin does the same, the farming of precious metals and the farming of subterranean food, with the express dogma of causing the least impact possible on nature.
I know this is a small request affecting an army of one person... me.... but it really would be a great addition to dwarves to allow Druids to worship Dumathoin. It makes good rp sense considering his history and teachings, and would mean The keepers of the natural areas under the mountain can be nature priests. The only way now for a Dwarven druid within the Morindinsamman is through Thard Harr who is the patron of jungle dwarves, not a very under the mountain king of feel.