Rumex crispus Curly dock
I think I have identified this correctly, but I am not 100% certain. This pretty dock is native to Europe and west Asia, though it has now naturalised on other continents and classed as a pest. The curly leaves contain oxalic acid and have been used as a green vegetable, but have to be boiled many times to dilute the oxalic acid, which may cause kidney stones. The leaves are used on the skin to relieve irritation and rashes. The leaves also contain Vitamins A and C.