From an image on opengameart.org shared by rubberduck.
Source Firkin
You know you love wood patterns, so here’s one more.
Source Richard Tabor
A seamless stone-like background for blogs or any other type of websites.
Source V. Hartikainen
Tiny circle waves, almost like the ocean.
Source Sagive
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
One of the few full-color patterns here, but this one was just too good to pass up.
Source Alexey Usoltsev
Prismatic Groovy Concentric Background
Source GDJ
A bit like some carbon, or knitted netting if you will.
Source Anna Litvinuk
The base gradient edited so now more details are rendered.
Source Lazur URH
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
From a drawing in 'Handbook of the excursions proposed to be made by the Lincoln Diocesan Architectural Society, on the 27th and 28th of May, 1857', Edward Trollope, 1857.
Source Firkin
Background pattern originally a PNG drawn in Paint.net
Source Firkin
Colour version of the original pattern.
Source Firkin
Nasty or not, it’s a nice pattern that tiles. Like they all do.
Source Badhon Ebrahim
A seamless pattern the starting point for which was a 'light rays' rendering in Paint.net.
Source Firkin
A bit of scratched up grayness. Always good.
Source Dmitry
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
ZeroCC tileable beechwood wood texture, generated in Neo Texture Edit by me. CC0
Source Sojan Janso
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
More in the paper realm, this time with fibers.
Source Jorge Fuentes
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
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