Salad burnet
From Cookipedia
Salad burnet is a biennial plant which can grow up to 4 feet high and its leaves consist of 4 to 12 pairs of tooth-shaped leaflets. The flowers are usually gathered on the edge of the green stems and are often tinged with purple. It inhabits dry grasslands Europe.
The leaves are used as a culinary herb and have a light taste of cucumber. It can easily be grown in large pots or in the ground in the UK and is a useful herb in dressings and salads.