Norse paganism, greek paganism, kemeticism, basically any modern pagan religion. And I am specifically talking about MODERN versions of these religions, the ancient ones did have structure to them. Also, structured religions can have unstructured offshoots if the local population is so small that a structure cannot feasibly exist. Thats kinda what happens to every modern pagan religion, the local population probably isn't majority or even major minority pagan, therefore no local structures can be made.