Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
These dots are already worn for you, so you don’t have to.
Source Matt McDaniel
This one is amazing, truly original. Go use it!
Source Viahorizon
A classic dark tile for a bit of vintage darkness.
Source Listvetra
Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
A repeating background with dark brown stone-like texture and abstract pattern that looks like tree trunks.
Source V. Hartikainen
A repeating background of thick textured paper. Actually, it turned out to look like something between a paper and fabric.
Source V. Hartikainen
Tiny circle waves, almost like the ocean.
Source Sagive
Abstract Stars Geometric Pattern Prismatic No Background
Source GDJ
A light gray background pattern with seamless fabric-like texture and almost unnoticeable stripes.
Source V. Hartikainen
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
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 dark background pattern that contains a steel grid pattern as a texture. Use it as a website background or for other purposes. It's free!
Source V. Hartikainen
A version without colours blended together to give a different look.
Source Firkin
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
From a drawing in 'A Life Interest', Mrs Alexander, 1888.
Source Firkin
A seamless pattern formed from a tile made from page ornament 22. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless background pattern with impressed gray dots.
Source V. Hartikainen
The image is a design of blue glass.How about using it as background image?
Source Yamachem
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
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
Did anyone say The Hoff? This pattern is in no way related to Baywatch.
Source Josh Green