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
Semi-light fabric pattern made out of random pixels in shades of gray.
Source Atle Mo
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
Feel free to use this seamless background texture as a background on a web site. It's colored in a light pink color and is seamlessly tile-able.
Source V. Hartikainen
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
That’s what it is, a dark dot. Or sort of carbon looking.
Source Tsvetelin Nikolov
Prismatic Snowflakes Pattern 2 No Background
Source GDJ
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
A new take on the black linen pattern. Softer this time.
Source Atle Mo
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Got some felt in my mailbox today, so I scanned it for you to use.
Source Atle Mo
The following repeating website background is colored in a blue gray color and resembles a concrete wall or something similar to it.
Source V. Hartikainen
Dark pattern with some nice diagonal stitched lines crossing over.
Source Ashton
Prismatic Groovy Concentric Background No Black
Source GDJ
CC0 and seamless wellington boot pattern.
Source SliverKnight
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Black & white version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Seamless SVG vector and JPG backgrounds with faded diagonal stripes. The colors are editable.
Source V. Hartikainen