CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
8 by 8 pixels, and just what the title says.
Source pixilated
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 design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
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
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
Someone was asking about how to achieve a fur pattern at #inkscape irc so tried to make a filter on it. Flood filled fractal noises rigged together. May someone find a good use for these.
Source Lazur URH
You know I’m a sucker for these. Well-crafted paper pattern.
Source Mihaela Hinayon
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
This texture looks like old leather. It should look great as a background on web pages.
Source V. Hartikainen
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin
Prismatic Abstract Geometric Background derived from an image on Pixabay.
Source GDJ
A blue gray fabric-like texture for websites. An yet another fabric-like texture. It has subtle vertical and diagonal stripes to it.
Source V. Hartikainen