A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Remixed from a raster on Pixabay, that was uploaded by ArtsyBee.
Source Firkin
Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Remixed from a drawing in 'Paul's Sister', Frances Peard, 1889.
Source Firkin
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
A free background pattern with abstract green tiles.
Source V. Hartikainen
This was formed by distorting an image of a background on Pixabay.
Source Firkin
This yellow background consists of a pattern of glossy gold buttons arranged in polka dot style on a seamless texture. Here's a pale yellow background pattern. Feel free to use it for your needs!
Source V. Hartikainen
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
This one is super crisp at 2X. Lined paper with some dust and scratches.
Source HQvectors
Retro Circles Background 7 No Black
Source GDJ
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Derived from an image that was uploaded to Pixabay by mdmelo.
Source Firkin
With a name like this, it has to be hot. Diagonal lines in light shades.
Source Isaac
Luxury pattern, looking like it came right out of Paris.
Source Daniel Beaton
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
I love cream! 50x50px and lovely in all the good ways.
Source Thomas Myrman
Derived from a JPG that was uploaded to Pixabay by ractapopulous
Source Firkin
Here's a tile-able wood background image for use in web design.
Source V. Hartikainen
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
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
A free background image with a seamless texture of cardboard. This texture of cardboard looks quite realistic, especially when is actually tiled.
Source V. Hartikainen