I have grown a few different species of Campanula and it doesn't ring a bell.
https://www.google.co.uk/searc...
There's something frustratingly familiar about it which I can't quite place! The single leaves still look like lettuce but the whole plant doesn't.
There is a similarity to one dwarf plant you posted..
http://www.alpine-seeds.com/ga...
The browser bar gives a species name of Campanula lasiocarpa, the leaf margins are a little different but the base/stem is similar.
https://www.google.co.uk/searc...
There's a lot of species and hybrids, see if you get flowers next year.
