This was formed by distorting an image of a background on Pixabay.
Source Firkin
A seamless pattern the starting point for which was a 'light rays' rendering in Paint.net.
Source Firkin
Prismatic Polka Dots Mark II 3 No Background
Source GDJ
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
From a drawing in 'A Life Interest', Mrs Alexander, 1888.
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
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
This seamless pattern consists of a blue grid on a yellow background.
Source V. Hartikainen
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
I scanned a paper coffee cup. You know, in case you need it.
Source Atle Mo
Black brick wall pattern. Brick your site up!
Source Alex Parker
The following free background pattern has glossy diagonal stripes as a texture to it, and it's colored in a light blue gray color. This background pattern is suitable for using in web design or any other graphic design projects. This applies to all background patterns here.
Source V. Hartikainen
An emulated “transparent” background pattern, like that of all kinds of computer graphics software.
Source AdamStanislav
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
The image is a seamless pattern of a fishnet.
Source Yamachem
This is so subtle you need to bring your magnifier!
Source Carlos Valdez
Abstract Tiled Background Extended 8
Source GDJ
Remixed from a drawing in 'A Girl in Ten Thousand', Elizabeth Meade, 1896.
Source Firkin
Fix and cc0 to get the tile this is based on.
Source SliverKnight
A light background pattern with diagonal stripes. Here's a simple light striped background for you.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin