To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless background texture of old cardboard.
Source V. Hartikainen
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
A free web background image with a seamless concrete-like texture and an Indian-red color.
Source V. Hartikainen
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
A very dark asfalt pattern based off of a photo taken with my iPhone.
Source Atle Mo
A seamless texture of an abstract wall colored in shades of light orange brown.
Source V. Hartikainen
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Prismatic Curved Diamond Pattern 7 No Background
Source GDJ
Submitted as a black pattern, I made it light and a few steps more subtle.
Source Andy