I'm cheating a bit today, because I'm not sure I've actually eaten sorrel this week, but I have been harvesting it for a while. This is a common herb that grows abundantly in and around my garden. It grows amongst grass, which I failed to cut back in the autumn, so the little sorrel leaves are struggling to find their way through mounds of dry grass.
These leaves have a sharp, lemony flavour, caused not by citric acid as the taste suggests, nor acetic acid, as the Latin name implies, but oxalic acid, as found in rhubarb. This can contribute to kidney stones, but as it is apparently also present in rather a long list of healthy foods, it's probably not worth avoiding sorrel for the sake of oxalic acid. To quote somebody or other,
No one ever died of an overdose of rhubarb crumble.
A few sorrel leaves make a pleasant addition to a salad, and can be added to sauces and suchlike in place of lemon juice, though you do have to use a fair bit of it. One unfortunate feature is that as soon as it gets hot, the colour changes from bright green to a dull and unappealing khaki. It still tastes good, though.
Also harvesting this week:
leek (the last one)
evening primrose roots
peas (the last from the garden last summer, which were only fit for soup, so have been in the freezer for some time)
Foraged food challenge summary page here.