This small unobtrusive fern grows at the foot of a slope, near the edge of a wood. Its fronds of a beautiful clear green emerge from a long underground rhizome. It is a Limestone fern (Gymnocarpium robertianum).
You have really to bend down to see its finely incised fronds. If you turn a frond (carefully, it is fragile!) you notice the sores, masses of spores, in regular rows on its backside.