I just moved into a house on a golf course with giant fir trees. In our yard in the grass is a fairy ring. Is this good or bad?
Fairy rings are neither good nor bad. They indicate that normally-occurring soil fungi are decomposing dead organic matter in the ground. The ring will gradually enlarge through the years, as the fungus works from a central point outward. The size of your ring indicates it’s been there for a number of years. The mushrooms develop only when conditions of soil moisture and temperature are suitable. The mushrooms can be left in place to degrade in a natural manner, or you can collect and discard them. No treatment is needed, or useful.