i have a bunch of little round cactusses in my yard about the size of a hand, with needles finer than a needle on them, and somebody mentioned to me that they're edible. if they are, how do you cook them?
I wouldn't advice it until you get a proper id (maybe I'm being over cautious), but at least some cacti are edible. I've been told that grocery store cacti is best served when cut into thin strips and then cooked in whatever manner you might cook green beans in.
Nopal (prickly pear) are edible. the leaves should be the size of a small woman's hands, at least and the (usually) pink fruit (tuna) makes a great jelly/compote/ warm ice cream topiing.
It depends on the breed, and your use for it. Some folks make a GREAT tasting candy from the Priclky Pear fruit. And if survival is your use, (These are Protected in some states!) The "Barrel Head" can save your life. One survival test I've learned that works, is to cut a peice and hold it to your lower lip. IF the lip begins to tingle or burn, DON'T eat it!
if it's prickly pear (or any type of opuntia), you peel the skin and spines off (some varieties do not need to be peeled and are spineless to begin with), cut into thin strips and lightly sautee them. They very closely resemble green beans when cooked this way. They are not so good if overcooked, so be careful about that. You can also steam them and the fruit, I hear, is very yummy and full of vitamins.
You probably shouldn't eat it unless you know exactly what it is. There are edible types of cactus (some of them very tasty) but there are many that have strange organic chemicals in them and will either not taste good or may make you sick. If they are edible you can roast over a fire, boil, stir fry, or anything that you do to cook regular vegetables.
When you pick a prickly pear do so with a thick glove or cloth as the fruit has tiny pricks on the outside that take a while to remove from you skin. They are classified as a noxious weed in Australia as for a while they started spreading wildly and an introduced Cactoblastis moth, was brought in to control it. I am pretty sure there are some other cacti that produce edible fruits.
I've had prickly pear fries while in Arizona... they're SO great! I love them... I wish I could grow them here outdoors but I can't... and the indoor ones never get quite big enuf...