Should you find yourself in need of a sharp edge, whether to cut a rope, skin a critter, or whittle friction fire-making tools, the basic ingredients required to make a flint knife can be found in most wilderness areas of the country.
You will need only two things — both of them are rocks. First, find a chunk of flint (or chert, chalcedony, jasper, obsidian, etc) to break into sharp tools. Flint can often be found in and around rocky ledges, river bottoms, and outcroppings, particularly if there is limestone present. Second, find a roundish rock about the size of a small apple to use as a hammerstone. This can be picked up anywhere – creek bottoms are a good place to find nice round ones.
It’s a good idea to collect some flint nodules and break them up for practice. Getting a sharp stone edge for your flint knife is pretty simple, but takes some experience to know how to strike the flint (a technique known as “knapping”) to make it break just right. It’s better to learn ahead of time rather than when you need a tool in an emergency.