A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A seamless pattern formed from a tile made from ornament 22. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
This one is something special. I’d call it a flat pattern, too. Very well done, sir!
Source GetDiscount
"Beige Stone", Tileable Texture.
Source V. Hartikainen
Inspired by a pattern I saw in a 19th century book. This seamless pattern was created from a square tile. To get the tile, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
Prismatic Snowflakes Pattern No Background
Source GDJ
Original seamless pattern with an Inkscape filter.
Source Firkin
I love cream! 50x50px and lovely in all the good ways.
Source Thomas Myrman
A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski
Not the most creative name, but it’s a good all-purpose light background.
Source Dmitry
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
Here's a seamless brown cork board background texture. Feel free to download or reshare if you like.
Source V. Hartikainen
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin
Remixed from a drawing in 'Jezebel's Daughter', Wilkie Collins 1880
Source Firkin
Zero CC tileable grass texture, photographed and made by me. CC0
Source Sojan Janso
Prismatic Abstract Line Art Pattern Background
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Zero CC tileable hard cover red book, scanned and made by me. CC0
Source Sojan Janso