Campanula lactiflora 'Pritchard's Variety' is one of my favourite perennials for cutting.
I had to cut my plant of this back hard in June (see here) but it has given me lots of good bunches of late flowers plus enough for little jars of them to sit around the place, the fresh and pretty blue making me think it is still summer here!
The card is Lemons on Grey by Mary Ford, and the painting is Japanese Steam by one of my favourite artists Christine McArthur.