We bought several little pots of COLUMBINE at the arboretum plant sale and they have rewarded us by multiplying like crazy. There are many varieties of Columbine (Aquilegia) and I'm not sure which ones we have, but they're all beautiful.
There are red and purple varieties on the Rock Garden Hill. The red has crept down the hill to mix with the sedum and we're trying to keep it pinched back, but I have a feeling all the pinching is only encouraging it to spread more. It's pretty stuff, though, even after it's finished blooming late-spring. It looks especially nice beside the rocks on Rock Garden Hill and Boulder Hill.