Number five from the same submitter, makes my job easy.
Source Dima Shiper
Prismatic Rounded Squares Grid 4 No Background
Source GDJ
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
This background pattern contains a texture of yellow wood planks. I think it looks quite original.
Source V. Hartikainen
There are many carbon patterns, but this one is tiny.
Source Designova
Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
This one needs to be used in small areas; you can see it repeat.
Source Luca
Super subtle indeed, a medium gray pattern with tiny dots in a grid.
Source Designova
Paper model of a tetrahedron. Modelo de papel de um tetraedro.
Source laobc
Based on an image that was uploaded to Pixabay by devanath
Source Firkin
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
Spice up your next school project with this icon background.
Source Swetha
The Grid. A digital frontier. I tried to picture clusters of information as they traveled through the computer.
Source Haris Šumić
A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
Remixed from a drawing in 'Line and form", Walter Crane, 1914.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Everyone loves a diamond, right? Make your site sparkle.
Source AJ Troxell
A pattern formed from a photograph of a 16th century ceramic tile.
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
Prismatic Abstract Geometric Background 5
Source GDJ
This is a remix of "blue wave-seigaiha".I hope this subtle color version of Seigaiha would be suitable for background .
Source Yamachem
First pattern tailor-made for Retina, with many more to come. All the old ones are upscaled, in case you want to re-download.
Source Atle Mo