Very simple, very blu(e). Subtle and nice.
Source Seb Jachec
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
Prismatic Triangular Seamless Pattern III With Background
Source GDJ
There are many carbon patterns, but this one is tiny.
Source Designova
A light brushed aluminum pattern for your pleasure.
Source Tim Ward
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Washi (和紙?) is a type of paper made in Japan. Here’s the pattern for you!
Source Carolynne
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Same as Silver Scales, but in black. Turn your site into a dragon with this great scale pattern.
Source Alex Parker
Zero CC tileable pine bark texture, photographed and made by me. CC0
Source Sojan Janso
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
I skipped number 3, because it wasn’t all that great. Sorry.
Source Dima Shiper
From a drawing in 'An Old Maid's Love. A Dutch tale told in English', Maarten Maartens, 1891.
Source Firkin
Same classic 45-degree pattern, dark version.
Source Luke McDonald