Hi, some ferns stay evergreen, I have polystychum and crytomium fortunei, you could try bergenia varieties in between but they can spread you would need to split after a time

Primroses and snowdrops would be my favourites in this situation.

Add Cyclamen coum to the list. Flowering beautifully now.

some of the Ajuga are variegated or bronze leaved. also consider some of the smaller Heuchera. Both species enjoy the conditions that the ferns do.
As said some Ferns are evergreen and will be worthy of a place in your fernery.

You might try Arum maculatum Italicum. The leaves disappear in summer but are very attractive just now. (and there are red berries in Autumn if it flowers)

Helleborus niger, Evergreen grasses - carex etc, tellima, heuchera, parahebe, sarcococca, euphorbia, euonymus..I have these with my ferns. But also, use some evergreen ferns like the Hart’s’ Tongue which looks great in winter.

there is also pachysandra and evergreen slow growing ground cover. produces white flowers too :o)