A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Continuing the geometric trend, here is one more.
Source Mike Warner
A light background pattern with diagonal stripes. Here's a simple light striped background for you.
Source V. Hartikainen
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
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
More bright luxury. This is a bit larger than fancy deboss, and with a bit more noise.
Source Viszt Péter
ZeroCC tileable mossy (lichen) stone texture, edited from pixabay. CC0
Source Sojan Janso
Prismatic Triangular Seamless Pattern III With Background
Source GDJ
A background tile for web with abstract repeating texture of dark "stone wall".
Source V. Hartikainen
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Seamless pattern formed from a tile that can be extracted 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
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
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
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Alternative colour scheme to the original.
Source Firkin
Number five from the same submitter, makes my job easy.
Source Dima Shiper
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
Prismatic Rounded Squares Grid 3 No Background
Source GDJ
A seamless pattern based on a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
One of the few full-color patterns here, but this one was just too good to pass up.
Source Alexey Usoltsev
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki