The double flowered form of Greater Celandine is an easy going short lived perennial that will lightly self seed in any sun or semi-shaded spot with enough moisture so once you have it you will probably always have it and like me I doubt that you will be upset. Excess plants are easily pulled out.
It grows to about 40cms. and its interesting foliage is evergreen and in spring it produces its full double yellow poppy like flowers that will brighten up any garden. I find it most useful in beds where other woodland style plants disappear for a length of time as it will furnish the bed with foliage in the mean time.