Most likely Ssp. verna based on the thinner petals.
Ficaria verna NS7143 30Apr2016 MJP
Ficaria verna 28Mar2016 NS7951 MP
Most likely Ssp. fertilis based on rounder, wider petals.
Ficaria verna NS7143 30Apr2016 MJP
Ficaria verna NS6058 12April2019 PW
Showing the tubers in the leaf axils of ssp. verna.
Ficaria verna ssp verna NS6373 20Apr2019 PW
Ssp. fertilis showing the fertile achenes.
from Cumbria Botany
Ssp. verna showing few fertile achenes.
from Cumbria Botany
Ssp. verna showing few fertile achenes and tubers in the leaf axils.
from Cumbria Botany
Ficaria verna - Lesser Celandine
This is a common woodland spring flower, though the leaves can remain until later in summer.
There are two sub-species:
Ssp. fertilis develops a full head of ripe achenes and tends to have larger and wider petals (10-20 x 4-9mm).
Ssp. verna develops tubers in the leaf axils after flowering and 0-few ripe achenes in the head.
Both forms over-winter by means of elongated tubers at root level: ignore the tubers developing at ground-level.
There are cultivar forms of both subspecies Ssp chrysocephala and ficariiformis respectively, both have larger flowers (mostly more than 15mm).
Greater Celandine is not in the same family.