Choose nettles with care as by now the older patches will be beginning to flower. Towards June they'll get gritty, dry and leggy and won't be fit for eating unless you can find a stand of them that's been mowed and is re-sprouting. You want the young fresh tips, with no flower tassels and nip off only the top few leaves from each stem for your soups & greens. Look out for sow thistle, which makes a good green veg., patches of chickweed (look in moist shaded places where it will thrive as a lush dense mat, in full sun it can get leggy and a bit stringy. Goosegrass or cleavers - just the very soft tips - can be cooked or steamed and go well with scrambled eggs, & if you can find them, young soft hop shoots (top 8" or so) are great in a quiche, likewise hogwed shoots (choose only very young still furled shoots though). Take loads of pictures, ask loads of questions and devour loads of id guides and wild food books and above all enjoy getting hooked on what can become an obsession if you're not careful - but above all....
(*nanny hat on*)
PLEASE take great care over identification - learn the look-alike baddies that will do you serious harm as well as those you want to try and if you're at all in doubt then please, please don't be tempted to go ahead & try stuff till you can be absolutely sure you really can identify your chosen harvest accurately. (*nanny hat off*)
P.S. That nettle brew is deffo for the plants, it does them a power of good so don't worry! And if you think that smells bad, comfrey's infinitely worse believe me...