This is Paeonia tomentosa, which was the very earliest to bloom. So far only one set of carpels has opened. This set had three, the lower two opened four days before the upper one, which is just opening in the photo.
What is curious about this one is that fertile seeds are a fleshy semi-opaque purpley red (almost jellybean-ish) when the carpel first opens-- as in the uppermost one-- look closely and you can see that some of the seeds are fully oval and large while others (the aborted ones) are flatter and smaller, as in the lower 2 carpels. After a few days the jellybeans darken to black and take on a harder look. But there are still some segments of red on some of those seeds. This is the first species in which I've seen the fertile seeds change colour so dramatically after the carpels open.