I have one! I just went out to check on things, and here was this 5-way poly on CHARIOTS OF GOLD, a 2012 intro by Tim Bell. It does look totally chaotic, though, as if it was going to be a 4-way and added the fifth petal at the last minute as an afterthought. And there are 5 sepals, although one is disguising itself behind that top right big petal. This one looks nothing like your gorgeous polys.
And I think I just learned something -- when you look at the bud, does the number of divisions there indicate how many petals/sepals there will be? I had no clue...
