Lesser celandine (Ranunculus ficaria) is a common spring plants that grows from root tubers. It is also known as 'Pilewort' because it is a herbal remedy for haemorrhoids in humans and there have been cases of hepatotoxicity as a result. It is a member of the buttercup family, so, theoretically, it might be poisonous. It is better left alone, although it won't matter if a few leaves make their way into picked forage because the leaves are not palatable and they will be left uneaten.