If it's from any store that sells commonly available peonies, it may be Mons. Jules Elie. Or it may be another light pink "Bomb" type peony. Bomb is the form of peony you describe, extremely full blooms.

If you go to this link & scroll down, there's a pic of it:

http://peonyparadise.com/index.asp?PageAction=VIEWCATS&Category=2&Page=6

Another possiblility of commonly sold peonies is "Sarah Bernhardt" - it's a very full "double" form. There's a pic here:

http://peonyparadise.com/index.asp?AdvSearchAction=GOFETCH&PageAction=ADVSEARCH&lngLookinCategoryID=0amp;txtSearchAllWords=lactiflora