ere Quite technically those would not be "true anarchists," and the definition of a true anarchist is pretty loose sometimes because any small group could have its own "government." It may be "human nature" to form a social contract, but I do not think that would constitute as "natural law," and it may be viewed as a natural right definitely if one believes in natural rights, but not natural law. Natural law would imply it happens 10/10 times, which we know it does not, because people under an authoritarian, closed border, restricted government do not and have not formed a social contract in any way under informed consent, unless of course they were the ones that overthrew a previous government to implement their own authoritarian regime.
Technically, people forming those small cooperatives would be closer to communists than anarchists, but they could very well be "anarcho-communists," whatever that would look like.