To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Derived from a drawing in 'Historiske Afhandlinger', Adolf Jorgensen, 1898.
Source Firkin
Abstract Ellipses Background Grayscale
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
Prismatic Abstract Geometric Background 5
Source GDJ
Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Might not be super subtle, but quite original in its form.
Source Alex Smith
The original enhanced with some gradients.
Source Firkin
Classy golf-pants pattern, or crossed stripes if you will.
Source Will Monson
Zero CC tileable bark texture, photographed and made by me. CC0
Source Sojan Janso
The image a seamless pattern of a wire-mesh fence.I want you to use this pattern as a lower layer.
Source Yamachem
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
Tile available in Inkscape using shift-alt-i on the selected rectangle
Source Firkin
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
Prismatic Curved Diamond Pattern 2 No Background
Source GDJ
Paper pattern with small dust particles and 45-degree strokes.
Source Atle Mo
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
A fun-looking elastoplast/band-aid pattern. A hint of orange tone in this one.
Source Josh Green