Pretty much anything that likes dappled shade; hosta, pulmonaria, solomon's seal, various dicentras, digitalis, epimediums, hellebores, etc. The possibilities are endless. I do suggest you get rid of the red mulch and use a natural mulch.

Not a difficult area at all.

I'd say, some plants that like good drainage would love that bed. And I have to wonder how much sun the bed gets, because the Iris is blooming there and they like sun.