From an image on opengameart.org shared by rubberduck.
Source Firkin
A seamless pattern formed from cross 4. To get the original tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
It has waves, so make sure you don’t get sea sickness.
Source CoolPatterns
Green Web Background, Seamless tile.
Source V. Hartikainen
A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
Might not be super subtle, but quite original in its form.
Source Alex Smith
Abstract Stars Geometric Pattern Prismatic No Background
Source GDJ
Bumps, highlight and shadows – all good things.
Source Badhon Ebrahim
Psychedelic Geometric Background No Black
Source GDJ
A seamless pattern formed from a modified version of rwwgub's tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
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
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
The image is a seamless pattern which is derived from a vine .Consequently, the vine got like dots via vectorization.The original vine is here:jp.pinterest.com/pin/500744052301410188/
Source Yamachem
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
A fun-looking elastoplast/band-aid pattern. A hint of orange tone in this one.
Source Josh Green
A seamless pattern formed from cross 4. To get the original tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A seamlessly tile-able grunge background image.
Source V. Hartikainen
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
Here I have tried to create something that would look like maple wood. Not sure how well it's turned out, but at least it looks like wood.
Source V. Hartikainen
Remixed from a drawing in 'An Index to Deering's Nottinghamia Vetus et Nova', Rupert Chicken, 1899. The unit tile can be had by selecting the rectangle in Inkscape and using shift-alt-i
Source Firkin