Feeding frenzy or .... !

I wish I knew the name of this plant.  I searched through my wild flower book but just couldn't find any plant that resembled this one.  I'm only including the photograph because it's the first time I have ever seen so many flies together on one flower head.  Even when I went a bit closer they didn't fly off.  Every flower head on the plant had two or three flies wandering about.  I presume they were feeding on the nectar but as I am no entomologist I might be way off the mark.