A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
Prismatic Abstract Background Design
Source GDJ
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
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
Light gray grunge wall with a nice texture overlay.
Source Adam Anlauf
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Classic 45-degree pattern, light version.
Source Luke McDonald
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Used a cherry by doctormo to make this seamless pattern
Source Firkin
A seamless pattern formed from a modified version of rwwgub's tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
Prismatic Abstract Geometric Background 5 No Black
Source GDJ
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin