Procedural Polka Dots Material 

UVs required: YES
Render Engine: CYCLES/EEVEE
Displacement: NO

How to use Mapping node with this material

Material Artist: Sanctus

This material is also sold as part of the Sanctus Library addon

along with hundreds of other materials.

You can also check other materials I made here

How to use the material

You can append the material to your scene by going to File>Append... navigate to the downloaded blend file containing the material, double click it, double click the Material folder, select the material and click the Append button. Once done you will be able to assign it to your object in your scene.