Sweet Violet is a British wildflower of woodland edges that is in decline. It produces blue/purple, scented flowers from March to May that provide nectar for woodand butterflies. This low-growing plant grows to 20cm tall and 30cm across in partial shade and a moist but well-drained soil. It will thrive when planted in a lawn underneath a deciduous tree (one that drops its leaves in autumn) and will spread over the years via horizontal stems (stolons).
 
It's flowers are edible and can be candied. It is believed that this wildflower is in decline because it is being foraged for culinary purposes (source: the Woodland Trust). Please don't forage wild plants, flowers or seed from nature. You can buy mature plants here or save money by growing them from seed (bought from a reputable source).