Here's a shader node group that generates a pattern that looks like those little ridges you see after the tide has gone out.

Made while experimenting, what you see is what you get: There are only basic inputs for Texture coordinates, Scale and displacement Amount; outputs for Shader and Displacement.

There are loads of things that could be added to make a general purpose sand shader but that would require a lot of nodes and create many inputs the would probably never be used. Basic changes can be made inside the node group.