I'm writing most of these off of my own experience or stories I've heard so part two will come when I find more ways.
~Donate plasma: They hook you up to a machine for about two hours and separate the plasma out of your blood. Pays anywhere from $25-$75 depending if you can get in a trial or how many times you've donated before. Your first time should take about four hours and decrease down to two after they finish the initial testing and know you're safe. WARNING CAN LEAVE TRACK SCARS
~Sell sell sell!: If you have anything you don't need or want at that moment or the foreseeable future sell it. Go ahead and sell it for cheap too, it'll save you bag space and remember five bucks can feed you for a day.
~Hobo chef: Get some bread, cheese, and butter. Make a hobo grill and make a ton of grilled cheese sandwiches. Then buy a cheap styrofoam cooler and wrap the grilled cheese sandwiches in some tin foil and stick them in the cooler to look legitimate. You can do this with hot dogs easily too. Go to a large event like a high school football game and sell for a buck a piece. Dress clean and cook them right to make more money, doing this improper can get you in trouble if people catch on to you.
~Dumpster dive: Go to places that sell video games and look for any games they've thrown out and sell them to Gamestop. Any places that might sell something of interest that's quick to sell usually has something useful in their dumpster. Use Craigslist to sell things you've found.
~Craigslist: Look under gigs and see who needs yard work done. If you have a skill see if you can use it to earn some cash. Writing and computer repair jobs are fast and easy to find on Craigslist. It's also better than standing on the corner with Mexicans
~Stand on the corner with Mexicans: shit pay and hard work. But hey a mans gotta eat right? Most of the work is cleaning, moving, or yard work. Expect to be tried to be cheated out of your money. Also if you speak English you have a higher chance of getting picked up than most.