Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
Might not be super subtle, but quite original in its form.
Source Alex Smith
The image depicts meshed silhouettes of various things.The original image is an OCAL clipart called "Enter FOSSASIA 2016 #IoT T-shirt Design Contest" uploaded by "openclipart".Thanks.
Source Yamachem
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
New paper pattern with a slightly organic feel to it, using some thin threads.
Source Atle Mo
Dead simple but beautiful horizontal line pattern.
Source Fabian Schultz
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Formed from a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
ZeroCC tileable moss texture, photographed and made by me. CC0
Source Sojan Janso
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Classy golf-pants pattern, or crossed stripes if you will.
Source Will Monson
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
This beige background pattern resembles a concrete wall with engravings or something similar to it.
Source V. Hartikainen
The tile this is formed from can be retrieved in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
ZeroCC tileable beechwood wood texture, generated in Neo Texture Edit by me. CC0
Source Sojan Janso
Abstract Arbitrary Geometric Background derived from an image on Pixabay.
Source GDJ