Common name : Wood Sorrel, Fairy Bell, Wood Sour, Cuckoo's Meat 

Physical appearance : These are the only plants in the UK to have three-heart shaped leaflets. There are several species all of which close their flowers and fold their leaves during the night or in harsh conditions. The flowers can vary in colour depending on species. The leaves can also vary in colour, depending on the species. There is a purple leaved species which has yellow flowers and should be avoided as food as it contains very high concentrations of oxalic acid. This is particularly important for anyone suffering with kidney complaints. Oxalic acid can be threatening to life for anyone suffering from kidney complaints. 

Edible parts : Leaves, stems and flowers

Best places to find : Roadsides, garden borers, cracks in paving

Time of year : Best collected between March and December

Serving suggestions : Very simply, sorrel makes a great addition to any leafy salad. Sorrel soup has declined in popularity lately but is in fact a very tasty dish (especially when served with sour cream). Sorrel also works as a great accompaniment to salmon.

NB - Please be sure you know what you are picking. Many plants look similar to one another and many can be poisonous! Please seek professional instruction if you are unsure! WOOD SORREL MAY BE HARMFUL TO THOSE SUFFERING WITH KIDNEY COMPLAINTS!

Photos courtesy of Jorg Hempel and Jon Sullivan via Wikipedia Creative Commons Attribution  

Drawings of Oxalis acetosella, from the 1885 German flora: "Flora von Deutschland Österreich und der Schweiz", Published 1885, Gera, Germany.