This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
The image is a remix of "edo pattern-samekomon".I changed the color of dots from black to white and added BG in light-brown.
Source Yamachem
Not sure if this is related to the Nami you get in Google image search, but hey, it’s nice!
Source Dertig Media
A light brushed aluminum pattern for your pleasure.
Source Tim Ward
Derived from a drawing in 'Historiske Afhandlinger', Adolf Jorgensen, 1898.
Source Firkin
Super dark, crisp and detailed. And a Kill Bill reference.
Source Badhon Ebrahim
This ladies and gentlemen, is texturetastic! Love it.
Source Adam Pickering
Same classic 45-degree pattern, dark version.
Source Luke McDonald
A seamless web background with texture of aged grid paper.
Source V. Hartikainen
This was formed by distorting an image of a background on Pixabay.
Source Firkin
The name is totally random, but hey, it sounds good.
Source Atle Mo
From a drawing in 'Jardyne's Wife', Charles Wills, 1891.
Source Firkin
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
A seamless background pattern of dark brown wood planks.
Source V. Hartikainen
Classy golf-pants pattern, or crossed stripes if you will.
Source Will Monson
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
A seamless pattern formed from a tile made from ornament 22. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Farmer could be some sort of fabric pattern, with a hint of green.
Source Fabian Schultz
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
Very simple, very blu(e). Subtle and nice.
Source Seb Jachec