From an image on opengameart.org shared by rubberduck.
Source Firkin
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
An abstract texture of black metal pipes (seamless).
Source V. Hartikainen
Sharp pixel pattern looking like some sort of fabric.
Source Dmitry
Prismatic Triangular Background Design Mark II 5
Source GDJ
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
Number 5 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
The image depicts a seamless pattern of Japanese Edo pattern called "kikkou-matsu" or "亀甲松" meaning " tortoiseshell-pinetree".The real pinetree is like this: https://jp.pinterest.com/pin/500744052301065077/
Source Yamachem
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
Super dark, crisp and detailed. And a Kill Bill reference.
Source Badhon Ebrahim
Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
An emulated “transparent” background pattern, like that of all kinds of computer graphics software.
Source AdamStanislav
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin