This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
Vector version of a JPG that was uploaded to Pixabay by theasad121
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
A seamless pattern formed from cross 4. To get the original tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Light and tiny, just the way you like it.
Source Rohit Arun Rao
A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
The image depicts a seamless pattern of a Japanese family crest called "chidori" in Japanese .A chidori in Japanese means a plover in English.
Source Yamachem
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Remixed from a drawing in 'Works. Popular edition', John Ruskin, 1886.
Source Firkin
It’s big, it’s gradient—and it’s square.
Source Brankic1979
This one resembles a black concrete wall when is tiled. It should look great, at least with dark website themes.
Source V. Hartikainen
Textured Red Brown Plastic, Free Background Pattern. Although there's already enough plastic in our lives, let's bring it to the web too.)
Source V. Hartikainen
Prismatic Polka Dots Mark II 2 No Background
Source GDJ
Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Inspired by a pattern found in 'A General History of Hampshire, or the County of Southampton, including the Isle of Wight', Bernard Woodwood, 1861
Source Firkin
Prismatic Floral Background No Black
Source GDJ
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