A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
Prismatic Geometric Tessellation Pattern No Background
Source GDJ
Number 5 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Here's a dark background pattern that contains a steel grid pattern as a texture. Use it as a website background or for other purposes. It's free!
Source V. Hartikainen
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
A version without colours blended together to give a different look.
Source Firkin
ZeroCC tileable moss texture, photographed and made by me. CC0
Source Sojan Janso
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Colour version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Love me some light mesh on a Monday. Sharp.
Source Wilmotte Bastien
More in the paper realm, this time with fibers.
Source Jorge Fuentes
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
Washi (和紙?) is a type of paper made in Japan. Here’s the pattern for you!
Source Carolynne
The name is totally random, but hey, it sounds good.
Source Atle Mo
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
A lovely light gray pattern with stripes and a dash of noise.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
A beautiful dark wood pattern, superbly tiled.
Source Omar Alvarado
Prismatic Abstract Geometric Background 2
Source GDJ
Prismatic Curved Diamond Pattern No Background
Source GDJ
A simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib
Remixed from a vector adapted from a jpg on Pixabay. The tile this is constructed from can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki