Stinging nettles! At first sight a nuisance, and not really welcome in the garden, but a useful plant nevertheless ----
Pick nettle leaves at the fully-formed but young, dark green stage. Boiled 50/50 with spinach is a v. good green veg., and apparently high in iron.
Pick anytime, but preferably before the mature "catkin" stage, loosely fill a bucket with the complete stem+leaves, and pour over boiling water. When cooled to tepid, soak your tired feet in the liquid - you'll be 'walking on air' afterwards, and it doesn't sting!
If you can gradually immunise yourself to the sting, it's not painful after a couple of years. The 'sting' is still there tho', but like beestings, promotes circulation and relieves rheumatism.