Many large patches of Few-flowered-garlic  (Allium Paradoxum) plants are growing alongside the local river banks.  It flowers earlier than Wild garlic or Ramsons (Allium Ursinum) and usually has only one flower but can have up to five which then are replaced by little bulbils which drop off.  Unfortunately it spreads rapidly and has become very invasive suppressing snowdrops, bluebells and other native plants and it is now illegal to plant them in the wild.  It was introduced to Britain in 1823 and first recorded in the wild near Edinburgh in 1863 and is found mainly in eastern and Southern Scotland and parts of eastern England but has spread further.  As a child I seldom saw it but now it is prolific locally particularly in damp areas and often grows near wild garlic which has much more noticeable flowers.