A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I. Version with black background.
Source Firkin
Prismatic Triangular Background Design Mark II 5
Source GDJ
Sometimes you just need the simplest thing.
Source Fabricio
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
This background has abstract texture with some similarities to wood.
Source V. Hartikainen
A seamless pattern of dark bricks. Maybe it's not very realistic, but it looks good in my opinion.
Source V. Hartikainen
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Fake or not, it’s quite luxurious.
Source Factorio.us Collective
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
One more updated pattern. Not really carbon fiber, but it’s the most popular pattern, so I’ll give you an extra choice.
Source Atle Mo
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso