I lost my gunnera, just as well probably! I was determined to fit it in my bog garden but they do become massive.
I have some calla lilies that used to flower beautifully, but haven't for a few years, some yellow & blue iris. I did have a dierama, angel's fishing rod but lost that too.
The things I have lost are either due to the harsh winters, or due to the hosta taking over a bit. After years of them being eaten by slugs, I managed to grow one as there's so many feet of gravel all around the bog probably. However now the novelty is wearing off, I guess I ought to tame it & let other things have room!
There are a lot of lovely plants that thrive in these conditions, but choose carefully.