Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
Zero CC tileable Crackled Cement (streaks) texture, photographed and made by me. CC0
Source Sojan Janso
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
A version without colours blended together to give a different look.
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Used in small doses, this could be a nice subtle pattern. Used on a large surface, it’s dirty!
Source Paul Reulat
Submitted as a black pattern, I made it light and a few steps more subtle.
Source Andy
Remixed from an image that was uploaded to Pixabay by KirstenStar
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
This texture looks like old leather. It should look great as a background on web pages.
Source V. Hartikainen
From an image on opengameart.org shared by rubberduck.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from a drawing in 'Prehistoric Man: researches into the origin of civilisation in the old and the new world', Daniel Wilson, 1876.
Source Firkin
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
Derived from an image that was uploaded to Pixabay by TheDigitalArtist
Source Firkin
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
Colour version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A free seamless background with pink spots.
Source V. Hartikainen