This pack has some Cycles nodegroups I have created. There are 8 sample materials using these nodes.
included nodegroups are: procedural textures, combined mix nodes and a few more if you want to know what a node is doing / how it works you can see the effect in the sample materials.
WARNING: use blender 2.79 or newer, because it uses the principled shader in one case, also the brick smoothing of the brick texture is used in a few cases.
the HDRI used for lighting is included (which is CC0 too)