Tiny, tiny 3D cubes. Reminds me of the good old pattern from k10k.
Source Etienne Rallion
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
Free tiled background with colorful stripes and white splatter.
Source V. Hartikainen
More in the paper realm, this time with fibers.
Source Jorge Fuentes
Have you wondered about how it feels to be buried alive? Here is the pattern for it.
Source Hendrik Lammers
Zero CC tileable hard cover cells book texture, 4k, scanned and made by me. CC0
Source Sojan Janso
An attempt for cleaning up the original image in a few steps.
Source Lazur URH
A free seamless background texture that looks like a brown stone wall.
Source V. Hartikainen
Number 5 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Colour version of the original pattern.
Source Firkin
From a drawing in 'Hyde Park from Domesday-Book to date', John Ashton, 1896.
Source Firkin
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
Can never have too many knitting patterns, especially as nice as this.
Source Victoria Spahn
Colorful Floral Background No Black
Source GDJ
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
Looks like an old wall. I guess that’s it then?
Source Viahorizon
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
Otis Ray Redding was an American soul singer-songwriter, record producer, arranger, and talent scout. So you know.
Source Thomas Myrman
A free background pattern with abstract green tiles.
Source V. Hartikainen
Just what the name says, paper fibers. Always good to have.
Source Heliodor jalba
The texture of this background image has some similarities with leather, and it's colored in a dark brown color. So, if you are looking for a dark brown background image for your website, this may be an option for you.
Source V. Hartikainen
The starting point for this was drawn on the web site steamcoded.org/PolyskelionMaker.svg
Source Firkin
A seamless background pattern of dark brown wood planks.
Source V. Hartikainen
Green Background Pattern
Source V. Hartikainen
Sort of like the Photoshop transparent background, but better!
Source Alex Parker