In most vascular plants the young leaves are folded or they form a cylinder that unrolls. Ferns are different, their fronds are uncurling spirals. Now is the time to look for them. The following two should be easy to find.
The Tongue Fern (Asplenium scolopendrium) grows on steep and stony slopes in the shadow of trees.
And the Common Bracken (Pteridium aquilinum) covers the forest floor under oaks and chestnuts.