Here's the close-up (sorry it's horribly out of focus).

It's Campanula glomerata, clustered bellflower, Mama! A well-behaved Campanula! I don't know if the variety you saw is 'Superba' as pictured at the link below, but they all look pretty much the same! My favorite is 'Acaulis' because it's shorter and more compact than the others. I had one--until it got run over by another perennial and I waited too long to dig it up to move it back out into the sun. Plan to get another one some day, 'Acaulis', not the taller ones. The tall ones come in white too!

They shouldn't be hard to find!

Happy shopping,
Skybird

Here is a link that might be useful: Campanula glomerata

Thanks, Skybird. I was hoping you'd know! Gosh it was a beautiful shade of purple. It's on my list of "must haves" now.

Oh! That is gorgeous! I will have to grow this one day for sure! :D