Welcome.
In this tutorial we will be making these textures:

You will need these plug-ins:
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Edgemaster by n d
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Height Field to Normal Map by stinger (You only need the HeightToNormal.dll)
Thanks to csm725 for inspiration from
this tutorialLets get started

Step 1.First open a new canvas and fill it with a light gray. For this tutorial I used one size 600x600 and filled it with Hex: D8D8D8.
Step 2.Add a new layer, set colors to default (black and white) and Effects>Render>Clouds with a low scale setting.
Step 3.Do Effects>Distort>Crystalize. I used cell size 17.
Step 4.Now run Effects>Edgemaster with black color at maximum intensity
Step 5.Add a new layer and repeat steps 2-4.
Step 6.Flatten the image and apply Effects>Blurs>Gaussian Blur at default settings
Step 7.Effects>Noise>Add Noise with intensity: 45-50, color saturation: 0, Coverage: 100
Step 8.Effects>Noise>Median with radius: 2 and percentile around 70
Step 9.Duplicate this layer and, on the top layer, run Effects>Height Field to Normal Map, turn black and white and invert colors
Step 10.Move this layer to the bottom and change the blending mode of the top layer to multiply. Adjust opacity to your liking.
You now have your pebbles texture! Continue below to make the leather texture.Step 11.Invert colors on the top layer set to multiply. You might also want to duplicate this layer and reduce the opacity on the duplicated layer about halfway down.
Step 12.Flatten image, adjust brightness using Adjustments>Curves
Step 13.Add some color, Adjustments>Curves RGB mode
You now have your leather texture!Example of usage (with some further editing):

Alternative strangelooking outcome:

To make this use a brown colored pebbles texture with a black and white leather texture in a layer above set to difference:
