Black brick wall pattern. Brick your site up!
Source Alex Parker
Abstract Arbitrary Geometric Background derived from an image on Pixabay.
Source GDJ
Might not be super subtle, but quite original in its form.
Source Alex Smith
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
Prismatic Groovy Concentric Background 3
Source GDJ
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
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
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Dark, crisp and subtle. Tiny black lines on top of some noise.
Source Wilmotte Bastien
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
An abstract pale yellow paper-like background with stains colored in yellow and green.
Source V. Hartikainen
Formed by distorting the inside front cover of 'Diversæ insectarum volatilium : icones ad vivum accuratissmè depictæ per celeberrimum pictorem', Jacob Hoefnagel, 1630.
Source Firkin
A grayscale fabric pattern with vertical lines of stitch holes.
Source V. Hartikainen
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Original minus the background
Source Firkin
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
A free seamless texture of reptile skin colored in a dark brown color. As always, you may use it as a repeated background image in your web design works, or for any other purposes.
Source V. Hartikainen
These dots are already worn for you, so you don’t have to.
Source Matt McDaniel
A free pink background pattern.
Source V. Hartikainen