The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Everyone needs some stardust. Sprinkle it on your next project.
Source Atle Mo
Prismatic Groovy Concentric Background 4
Source GDJ
Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
Seamless Light Background Texture.
Source V. Hartikainen
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
A repeating background with wood/straw like texture.
Source V. Hartikainen
Light gray grunge wall with a nice texture overlay.
Source Adam Anlauf
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
A seamless pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
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
It was called Navy Blue, but I made it dark. You know, the way I like it.
Source Ethan Hamilton
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight