CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
From a drawing in 'La Principauté de Liège et les Pays-Bas au XVIe siècle', Société des Bibliophiles Liégeois ,1887.
Source Firkin
Smooth Polaroid pattern with a light blue tint.
Source Daniel Beaton
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
Sounds like something from World of Warcraft. Has to be good.
Source Tony Kinard
Retro Circles Background 4 No Black
Source GDJ
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
Everyone loves a diamond, right? Make your site sparkle.
Source AJ Troxell
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Here's a new paper-like background for free use on personal and commercial projects (this applies to all background patterns here).
Source V. Hartikainen
It has waves, so make sure you don’t get sea sickness.
Source CoolPatterns
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett