A pack of free materials called Surfaces Lite.
The project is still in development and more material will be added in the future, so stay tuned.
You can always upgrade for $ 14.99 and get more than 96 surfaces. The creators update the library with more than 20 new materials every 15 days, so the pack is definitely worth it. You can follow the progress on Facebook or send them an email to request a new material.