Seamless pattern inspired by a drawing on Pixabay. To get the tile this is formed from, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
From a drawing in 'Uit de geschiedenis der Heilige Stede te Amsterdam', Yohannes Sterck, 1898.
Source Firkin
To get the repeating unit, select the rectangle in Inkscape and use shift+alt+i
Source Firkin
Nice little grid. Would work great as a base on top of some other patterns.
Source Arno Gregorian
Seamless Prismatic Pythagorean Line Art Pattern No Background. A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.
Source Firkin
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
If you don’t like cream and pixels, you’re in the wrong place.
Source Mizanur Rahman
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
A lovely light gray pattern with stripes and a dash of noise.
Source V. Hartikainen
A free pink background pattern.
Source V. Hartikainen
This background has abstract texture with some similarities to wood.
Source V. Hartikainen
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin