Strange mushrooms on #10 green

I've seen mushrooms on greens before, but these are new to me.  However, they are not new to this very specific location, the back portion of the green on the tenth hole.

According to staff members, these mushrooms reappear every winter and go away in spring.  They grow just below the surface and are hollow.  The tops of the mushrooms push through the surface of the green and are mowed off, leaving a small mushroom cup that is visible as a small hole on the green's surface.  The surrounding turf might be browned out from the water repelling influence of the mushrooms, but more likely is damaged from scalping by our mowers as the mushrooms raise the surface above a normal grade.

In the last photo, you can see our effort to plug out some of the mushrooms and replace with turf from our nursery green.  The plugs are darker because the turf is all bentgrass and is mowed a bit higher than the tenth green.  So why are the mushrooms here?  It may be fairy ring, a common disease on greens and most likely, the culprit in this instance as well.

 We will be treating this location with a fungicide tomorrow afternoon in hopes of knocking back the mushrooms.  I'm told that the affected area expands each season since it's arrival, 7 years ago, when the greens were sodded.  We certainly do not want this condition to spread beyond its current borders.

Until it is controlled or seasonal changes phase out the fungus, we will keep the pin location in the front or middle portions of the green