More of the most common sort of fly on the stinkhorn--Flat-footed flies, Platypezidae. These were possibly genus Platypeza as Brimley (1) lists only that genus for North Carolina at this season (October). This also agrees with seasonal listing for Platypeza at Insects of Cedar Creek, Minnesota. Flies were clustered around the top of the cap, where there is a large white spot of mushroom flesh poking through the brownish cap.

However Jeff Skovington believes these to be Melanderomyia--see comments under other images.
Male (large eyes) is in foreground. Female (smaller eyes) is in background.

Whole mushroom, with its fly associates: