From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
A bit strange this one, but nice at the same time.
Source Diogo Silva
The image depicts an edo-era pattern called "same-komon" or "鮫小紋"which looks like a shark skin.The "same" in Japanese means shark in English.
Source Yamachem
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
Abstract Tiled Background Extended 6
Source GDJ
A seamless gray background texture suitable for use on websites. To me, it has the look of stone. Feel free to modify it to meet your needs (by making it a bit lighter or darker, for example).
Source V. Hartikainen
A repeatable image with dark background and metal grid pattern.
Source V. Hartikainen
A simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib
This background has abstract texture with some similarities to wood.
Source V. Hartikainen
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
It’s a hole, in a pattern. On your website. Dig it!
Source Josh Green
Derived from an image that was uploaded to Pixabay by mdmelo.
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
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
A seamless green background texture. The image is distributed under a Creative Commons License (like all of the images here).
Source V. Hartikainen
An abstract Background pattern of purple twisty patterns.
Source TikiGiki
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Abstract Geometric Background derived from an image on Pixabay.
Source GDJ
Coming in at 666x666px, this is an evil big pattern, but nice and soft at the same time.
Source Atle Mo
Redrawn based on a drawing in 'По Сѣверо-Западу Россіи' Konstantin Sluchevsky, 1897.
Source Firkin
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
This one looks like a cork panel. Feel free to use it as a tiled background on your blog or website.
Source V. Hartikainen
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic