Japanese gold: Hylomecon japonicum
I grew this stunning little Japanese poppywort many years ago in Boulder...and fitfully since. We had a flashy clump or two persist at the Gardens a few years, and like all good things, it disappeared (didn't propagate, you see). So what do you do when you have a great clump of something like this? There is only one good answer to a question like that: what you do is bust it up. This year I finally dug up almost half the plant for Karen Lehrer, and a chunk for Mike Kintgen. That's what you do if you want to keep a plant: give it away!
I am sure my show may be diminished for a year or so: but with some fresh compost in the hole, it will be sure to respond the year afterwards and thenceforward.
There are a few mail order sources for this gem: put it in part shade (mine is growing with lusty clumps of waterlily Colchicum and Iris cristata. Mark the spot they are growing (they go dormant in summer) and sit back and enjoy!