Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
The image depicts a seamless pattern of pine tree leaves.
Source Yamachem
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
From a drawing in 'Bond Slaves. The story of a struggle.', Isabella Varley, 1893.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Prismatic Abstract Geometric Background 5
Source GDJ
Number five from the same submitter, makes my job easy.
Source Dima Shiper
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
It’s a hole, in a pattern. On your website. Dig it!
Source Josh Green
Pattern Background, Texture, Photoshop Structure style CC0 texture.
Source Darkmoon1968
The image depicts a seamless pattern of Japanese Edo pattern called "kikkou-matsu" or "亀甲松" meaning " tortoiseshell-pinetree".The real pinetree is like this: https://jp.pinterest.com/pin/500744052301065077/
Source Yamachem
This seamless background image should look nice on websites. It has a dark blue gray texture with vertical stripes, it tiles seamlessly and, like all of the background images here, it's free. So, if you like it, take it!
Source V. Hartikainen
Number 3 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
A seamless pattern formed from a rectangular tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin