Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
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 hint of orange color, and some crossed and embossed lines.
Source Adam Anlauf
This yellow background consists of a pattern of glossy gold buttons arranged in polka dot style on a seamless texture. Here's a pale yellow background pattern. Feel free to use it for your needs!
Source V. Hartikainen
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Background Wall, Art Abstract, Star Well & CC0 texture.
Source Ractapopulous
Imagine you zoomed in 1000X on some fabric. But then it turned out to be a skeleton!
Source Angelica
In the spirit of WWDC 2011, here is a dark iOS inspired linen pattern.
Source Atle Mo
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
A seamless background pattern with impressed gray dots.
Source V. Hartikainen
A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
A re-make of the Gradient Squares pattern.
Source Dimitar Karaytchev
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A nice looking light gray background pattern with diagonal stripes.
Source V. Hartikainen
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Remix from a drawing in 'Ostatnie chwile powstania styczniowego', Zygmunt Sulima, 1887.
Source Firkin
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin
More tactile goodness. This time in the form of some rough cloth.
Source Bartosz Kaszubowski
The edges of all the red objects line up either vertically or horizontally, but it doesn't appear so. Made from a square tile that can be got by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin