In the 'Repeat Performance' article of the Bushcraft mag it states that Lesser Celandine is an edible green. With careful preparation the tubers of this plant can be used as a wild food, and when the leaves are young they are edible, but I had concerns about the ediblity of the rest of the plant as they are a member of the Buttercup family and the tubers for one are poisonous raw, so I looked on the PFTF website and found this:
Young leaves in spring - raw or cooked as a potherb. The first leaves in spring make an excellent salad. The leaves, stalks and buds can be used like spinach, whilst the blanched stems are also eatenThe leaves turn poisonous as the fruit matures. Caution is advised regarding the use of this plant for food, see the notes above on toxicity. Bulbils - cooked and used as a vegetable. The bulbils are formed at the leaf axils and also at the roots. Caution is advised, see the notes above on toxicity. The flower buds make a good substitute for capers.