Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Gold Triangular Seamless Pattern No Background
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
Dark wooden pattern, given the subtle treatment. based on texture from Cloaks. https://cloaks.deviantart.com
Source Atle Mo
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
A seamless paper background texture colored in pale yellow. This seamless texture is ideal for those who need a yellow background image for their website. The texture resembles paper.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Super detailed 16×16 tile that forms a beautiful pattern of straws.
Source Pavel
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
The name is totally random, but hey, it sounds good.
Source Atle Mo
The starting point for this was a texture drawn with the 'Radial Colors' plug-in in Paint.net.
Source Firkin
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Coming in at 666x666px, this is an evil big pattern, but nice and soft at the same time.
Source Atle Mo
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
Might not be super subtle, but quite original in its form.
Source Alex Smith
This background image has seamless texture that resembles a surface of gray stone.
Source V. Hartikainen
A brown metallic grid pattern layered on top of a dark fabric texture. It should look great when using as a tiled background on web pages, especially blogs.
Source V. Hartikainen
Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
Dead simple but beautiful horizontal line pattern.
Source Fabian Schultz
This metal background pattern resembles a metal plate with rivets. Solid rivets on a metal plate.
Source V. Hartikainen
Number 5 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin