While temporarily staying at a small studio apartment in Los Angeles, California, I decided to try a little foraging for my dinner. It's surprising how much free food you can collect in a small radius in one of the world's largest population centers.
For example, in the tiny back courtyard of this studio, I collected fresh young dandelion leaves, flowering dandelion heads, sprigs of fresh green mint, some lemons from a citrus tree, rosemary from a neighbor's roadside bush and some fennel and mustard greens from an empty lot.
Right now I am drinking a refreshing lemon-mint beverage. I filled a wine glass with filtered water, squeezed 1/4 of a small (tennis ball sized) lemon into the water, and placed a gently crushed mint sprig in the glass. This tastes fresh and wonderful, is brimming with healthy nutrients, and cost me zero cash. Sugar or honey could also be added, and you can drink it all cold over ice or heated as tea. Or add some of the liquor of your choice.
I could use seltzer instead of the water, or replace the lemon with a fresh picked lime or grapefruit, and it would still be lovely.
If you are not in a warm area with citrus fruits, you could just use the mint (using more of it, simply muddle/crush the leaves and stems with some sugar into a minty paste) and a create a refreshing mojito - with or without the alcohol. Or dry the leaves to keep for making mint tea.
You can also use fresh rosemary like you would mint (it is in the mint family). Make a cold or hot rosemary beverage, with or without citrus, in water or seltzer - be inventive!
I also have the makings of some dinner from my little walk around the block. I collected young dandelion leaves and flowering dandelion heads, to add to lettuce with a few more mint leaves, making a healthy and very frugal salad. You can eat many found flowers in your salad - flowers from pansies, rose petals, day lily petals, violets and nasturtiums. Top off with anything else you find in your yard or garden (like a tomato, carrot, radish, or cucumber). For dressing, chop up your rosemary leaves with some olive oil, vinegar, salt, pepper and garlic, for a simple, healthy dressing. You can also make a yogurt-rosemary-pepper dressing. From my found fennel and mustard greens, I can add a little zing to the chicken, fish, potatoes or salad dressing.
If I had some chicken I could cook it with plenty of rosemary and garlic, with potatoes, for very little cash. Potatoes are extremely inexpensive. A little fresh garlic from the store goes a long way, or you could grow your own. The only splurge is for the chicken, if you eat meat. There are many fishes you could also prepare this way - trout, perhaps, that you caught yourself. Have your dandelions and mint on the side with rosemary dressing - you could even sautee the greens and flowers with some butter and garlic.
Many books on the market can help you learn to identify your local greens/flowers, and it is worth investigating what is in your own backyard, park, or nearby abandoned lot. Having a small garden can supplement what you find, and your found foods add interest and new nutrients to your staples.
Some wild food resource books from Amazon -
Edible and Useful Plants of California (California Natural History Guide)
Wild Edible Plants of Western North America