The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The name alone is awesome, but so is this sweet dark pattern.
Source Federica Pelzel
Inspired by a 1930s wallpaper pattern I saw on TV.
Source Firkin
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
A beautiful dark wood pattern, superbly tiled.
Source Omar Alvarado
Colorful Floral Background No Black
Source GDJ
An orange vertically striped background pattern. Feel free to download and use this orange background pattern, for example, on the web). It resembles a wallpaper with vertical stripes or something similar to it.
Source V. Hartikainen
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
Nasty or not, it’s a nice pattern that tiles. Like they all do.
Source Badhon Ebrahim
Sort of like the Photoshop transparent background, but better!
Source Alex Parker
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
This seamless pattern consists of a blue grid on a yellow background.
Source V. Hartikainen