The asset library LotPixel has been updated with over 1,350 free PBR texture sets. New textures include a range of natural stones, like marble and granite, and interior tiling.
Free users can download the texture sets in up to 8K resolution. They are provided as JPEG files with diffuse/albedo, ambient occlusion, glossiness, height, normal, roughness, and specular maps.
If you want more assets, including 3D models, decals, and textures in higher resolution, you should get a paid subscription, which costs $9/month for a Freelance subscription and $27 for an Indie one.