all you need is a plastic bag, a glove, and a place where nettles are growing. you can find nettles almost everywhere, i think. just make sure they're not too close to a road, or right by the path... (since dog-pee and exhaust/car-dirt etc etc are not welcome additions to soup). the little new leaves are the tastiest, so pick the tops off the plants.
then when you get home, wash them in hot water, which gets rid of the prickles, so then you can clean and sort them out without getting stung. you can just put the stalks and all in, if they're not big ones. rinse them again.
chop up an onion and some garlic cloves, and fry them a little bit in some oil. then add your nettles, and wild garlic if you have them, and water. you can add some bouillon if you like, or just salt and pepper. then let it boil up, till the nettles are soft, it doesn't take very long. then mix it all with a blender/mixer-stick, and your soup is ready.
you can also fry the nettles in some olive oil, just as they are; that's also very good.
nettles are really healthy, full of iron, and also of course completely fresh, local, and free! and best in the spring.