Glade in Meadows biome at night. There is Surtling Core as a reward on the stump. Valheimver a0.79.10
It is a small area with dirt covered ground and a stump-altar in the middle, surrounded by trees. It can be found in Meadows biome.
A group of Greydwarfs is usually protecting it. Upon defeating them, a random reward appears on top of the stump.