A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
A repeating background with wood/straw like texture.
Source V. Hartikainen
It looks very nice I think.
Source V. Hartikainen
A lovely light gray pattern with stripes and a dash of noise.
Source V. Hartikainen
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
Here's a seamless brown cork board background texture. Feel free to download or reshare if you like.
Source V. Hartikainen
A pattern drawn in Paint.net and vectorized in Inkscape.
Source Firkin
Just the symbols of the signs of the zodiac distributed in a chequer board-like pattern
Source Firkin
A repeating background of beige (or is it more vanilla yellow) textured stripes. One more background with stripes.
Source V. Hartikainen
Derived from a JPG that was uploaded to Pixabay by ractapopulous
Source Firkin
Luxurious looking pattern (for a T-shirt maybe?) with a hint of green.
Source Simon Meek
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Different from the original in being a simple tile stored as a pattern definition, rather than numerous repeated objects. Hence easy and quick to give this pattern to objects of different shapes. To get the tile in Inkscape, select the rectangle and use shift+alt+i.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
The base gradient edited so now more details are rendered.
Source Lazur URH
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i
Source Firkin
A bit of scratched up grayness. Always good.
Source Dmitry
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf