It looks Euphorbia-ish to me. (Couldn't find any matching Euphorbia, though.)

And did you notice that the flowers seem to come from inside paired bracts? You can see a bunch of these, most notably at about 5:30 relative to the visible flower. [I'm not sure if they are technically bracts or not, but that's the closest I can come.]

Re. petal count, did you see more than the single flower in the photo? Perhaps the one in the photo is not typical.

E. corollata at an early stage?

Interesting idea. Only the first flower open so far -- other flowers soon to follow from all those other pairs of bracts -- and the first flower was a bit hurried (being first) and got the number of petals wrong. And once the other flowers are open, it will look a lot more like E. corollata.

Sounds good to me.

Westmich, can you break a piece of stem and llok to see if it has whitish, milky sap? The gentlemen above are suggesting genus Euphorbia and that factoid is helpful in id'ing that bunch.

+oM

I think E. corollata is probably it, there is a lot of this plant growing in this area and I have photographed it often but in apparent later stages of growth; I think the unusual appearance of the flower and the overall shape of the plant is what threw me off but looking at some of my other E. corollata photos at the base of the plant, the leaf shape and habit seem to match this. I may try to confirm this later this spring and see if I can find some more plants in the same stage of growth. Thanks all.

All Euphorbias have white latex sap, a definitive clue (and something you'll want to wash off unless you want to find out experimentally if you're one of the unfortunate few who get a rash like poison ivy from getting that sap on their skin.)