There are links to some posts at the bottom of this page from 2010 about wild garlic, also known as bear garlic; latin name allium ursinum. It grows in damp woodland, often near a stream. In the South-west of England the leaves are visible and the flowers are still in bud form( close to the centre of the leaves near the ground) in March and the flowers may not come out until the end of April.
If you see a white flowering plant in the middle of the garlic, be careful that it is not a white woodland anenome that you are looking at as they grow in association with the garlic and come out earlier.
The anenomes leaves are quite different as are the flowers. Bluebells and lily of the valley are poisonous and these possibly are too, so if in any doubt, pick a leaf, rub it between your fingers and have a good smell, then you should know what it is! And if you are not sure of your identification skills, it’s not worth it.
The flowers come out later and the plant carries on growing well into May. You can pick and use the leaves when they are young and tender as well as when they are in full flower. Apparently you can dig them up and eat the little bulbs at the bottom, though I don’t dig up plants in urban woodland. A handful of garlic leaves goes a long way!
I think you can buy plants from the Garlic Farm on the Isle of Wight amongst other places.
Links to Nigel Slater’s wild garlic recipes in The Observer