Old comments below reflect an early assumption that these might be shining mold beetles:
There were several of these beetles on the closed blooms of this plant. These plants were in an open meadow maybe 100 ft. from a creek.
The beetles were roughly lady beetle sized, approx. 6mm in length.
The Peterson Beetle Guide (1)
says shining mold beetles are "common on flowers or foliage." It also mentions the antennae are oval 3-segmented clubs. I'm not sure if the antennae of these beetles matches that or not. You can see the antennae of the center beetle, but I'm not sure what the correct term for that type of antennae is.
The Peterson guide also states that the larvae live in the heads of flowers, so peharps that has something to do with the strange reddish bumps on the plant.