A seamless pattern based on a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
From a drawing in 'A Guide to the Guildhall of the City of London', John Baddeley, 1898.
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 with a unit cell drawn as a bitmap in Paint.net and vectorized in Vector Magic.
Source Firkin
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
This is so subtle: We’re talking 1% opacity. Get your squint on!
Source Atle Mo
Sounds like something from World of Warcraft. Has to be good.
Source Tony Kinard
A seamless green background texture. The image is distributed under a Creative Commons License (like all of the images here).
Source V. Hartikainen
This background image has seamless texture that resembles a surface of gray stone.
Source V. Hartikainen
From a drawing in 'Friend or Fortune? The story of a strange year', Robert Overton, 1897.
Source Firkin
Nasty or not, it’s a nice pattern that tiles. Like they all do.
Source Badhon Ebrahim
The image depicts polka dot seamless pattern.
Source Yamachem
I asked Gjermund if he could make a pattern for us – result!
Source Gjermund Gustavsen
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
Zero CC tileable brick texture, photographed and made by me. CC0
Source Sojan Janso
ZeroCC tileabel stone granite texture, edited from pixabay. CC0
Source Sojan Janso
This light blue background pattern is quite pleasing to the eye, it consists of a tiny rough grid pattern, which is seamless by design. That's it, if you like the color, you can use this seamless pattern in a web design without making any further modifications to it.
Source V. Hartikainen
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin