Yes they tend to be solitary. You may see a bit of variation in colour and height which may be due to growing conditions or it could be that there is more than one species. The taxonomy on this fungus is a bit hazy so it has been listed with 'group' after it's scientific name to cover this. It's a white spored fungus and if you feel keen and gently excavate one of them you should find a root-like structure at the base of the stipe. I've been told the length is determined by how far the buried wood it's growing from is under the ground.