Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
Luxurious looking pattern (for a T-shirt maybe?) with a hint of green.
Source Simon Meek
Inspired by a JPG that was uploaded to Pixabay by kokon_art
Source Firkin
This one needs to be used in small areas; you can see it repeat.
Source Luca
There are many carbon patterns, but this one is tiny.
Source Designova
This is lovely, just the right amount of subtle noise, lines and textures.
Source Richard Tabor
Vertical lines with a bumpy, yet crisp, feel to it.
Source Raasa
A comeback for you: the popular Escheresque, now in black.
Source Patten
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
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
A series of 5 patterns. That’s what the P stands for, if you didn’t guess it.
Source Dima Shiper
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
Sometimes you just need the simplest thing.
Source Fabricio
A repeating gloomy background image. This one consists of a pattern of black chains layered on top of a dark textured background.
Source V. Hartikainen
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Wasn't satisfied with the original's colouring. Too much component transfer and colormatrixes yet the results are lacking a bit. So this time it is a simple black to transparent fade, making it possible remixing easily once there will be other blending modes supported as well. Probably in inkscape 0.92.
Source Lazur URH
Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Prismatic Abstract Geometric Background 4 No Black
Source GDJ
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
A yellow tiled background... Blurriness, bokeh effect and rectangles pattern in one mix.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin