Coltsfoot

Tussilago farfara

NL: Klein hoefblad / F: Tussilage

Coltsfoot has been known as a powerful expectorant, demulcent, diaphoretic and antitussive in traditional herbalism, being prescribed for a wide range of respiratory ailments, from common colds and coughs, sore throats to bronchial asthma and chronic emphysema. It is also known for its skin healing properties, being used externally to treat eczema, inflammations, burns, skin ulcers, wounds and bites.

There are suggestions of coltsfoot extracts being used to increase immunity.  

Leaves are found separately from the flowers

The entire plant is known by foragers as a wild edible. I personally would only eat it unless in a situation of serious need, as the plant contains liver-harzardous pyrrolizidine alkaloids and is potentially toxic in large doses - especially the flowering stems. Such alkaloids are mostly destroyed by decoction. The leaves contain less of these alkaloids and are the safest part of the plant to be used. 

Here is a nice video with more information on identifying coltsfoot:

Identifying Coltsfoot, Tussilago farfara - My Nature Apps

More information and links to recipes with coltsfoot:

Coltsfoot - Tussilago farfara, by Celtnet