Empty Belly and Stinging Brains Serve You Righteously
Since I'm read by quite a few people that view the barren wastelands in between strip malls as the "wilderness" I've decided to provide those of you in that camp with four relatively easy ways to feed your characters during those desperate times when your Dungeon Master actually makes you keep track your resources and you run out of food and water.
Roots and Needles
One of the easiest things to have happen is to run out of drinkable water. It happens to the best of us. Now most every explorer worth his salt is going to have a metal cup in his bag and pan to cook on - and if he doesn't have one he's a fool - so making the water drinkable by boiling it over the fire isn't usually that difficult of a task.
Unfortunately there are times when your water may have a foul taste, even after a purify drink spell. The foul taste can be the result of your water being in a particularly acidic region, your pans and mugs being unclean, muddy water, or your Dungeon Master being a jerk. Whatever the case, once the liquid is safe to drink you're going to need to make it something your character can actually keep down. There are three really common plants that you can harvest to make the water more palatable: dandelions, pine needles, and mint. Of the three dandelions and pine needles will probably be the easiest to come by, though mint will be the most enjoyable of the three.
What you're going to want to do is to place some leaves in the water (roots if you're using the dandelion) once you've brought it to a boil as you would with tea. Now the longer you leave the leaves in there the stronger a taste you're going to find developing. This strength of flavor can mask not only the foul taste of the liquid but also the tell tale odors and tastes of certain poisons so if you're playing with a bunch of vipers prepare your own drink and offer to make theirs as well. You never know, they might remember that kindness and gladly take a bullet for you when you use them as human shields later.
The Sock Hop
Whether you're in a cave or out walking in the evening air bats will be fluttering by. Most of us see them skirting overhead in a crazy zig-zag pattern and avoid them like the plague, but in a pinch you can kill them fairly easily and eat them. The methodology for pulling this off is much the same as you could use for catching pigeons and other small birds.
Take a burlap sack and cut off a two foot section. Using the needle and thread you bought to help maintain your clothing - you did buy them right - sew the sack into a similar form as you tube sock. One end needs to be sewn shut and the other left open. Now you want to drop a handful of rocks into your burlap sock; tie off the other end. What you've effectively made is a cheap bola that you can now use to drop the flying appetizers from the sky and into your frying pan.
A word of caution in using this method. Your Dungeon Master is likely to try and get you with a disease carried by one of these small flying creatures. To reduce the likely hood of this occurring announce that you are going to skin, gut and clean the catch. After each step you're going to clean your hands to prevent yourself from getting sick. Then you're going to cook the critters on a stick over the fire. Cook them thoroughly, have the cleric cast purify food as an extra measure at the end and you can eat in peace.
Spoil the Child
A lot of people tend to look at fishing as something where you need to spend two hundred dollars on a rod and reel. Then of course you need the hat, vest, tackle box, and as many synthetic lures as you can stuff in them. Truth is you don't need any of that noise.
Cut a length of wood approximately six feet long. You want the limb to be about an inch thick at most (so about the length from the tip of your thumb to the first joint). For the line you can do a couple of methods that range from tearing blades of grass and weaving them together into a line; to finding thin vines that you can find in most every forest in the world; to using the thread you sew with (my preferred method). Making a hook requires that you either forage really well, bought one earlier, or like to carve. Whether you forge a piece of bone that you can fashion into a hook or widdle one from the river birch the end goal remains the same: you need the hook to form a J with a sharp point on the end.
What kind of bait you use is going to depend on how small you can make your hook. If you can get it small enough to use worms you'll just have to dig around any piles of leaves or old stumps. If you need to use something bigger to catch fish with you'll have to go hunting for grubs, large spiders, dragonflies and the like.
Once you have everything together toss it in the water, preferably in an eddy if you're on a river or near an embankment in a pond, and wait. If the fish are hungry you'll be in luck and if not well, there's always dynamite . . .