Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i
Source Firkin
The name alone is awesome, but so is this sweet dark pattern.
Source Federica Pelzel
This seamless background image should look nice on websites. It has a dark blue gray texture with vertical stripes, it tiles seamlessly and, like all of the background images here, it's free. So, if you like it, take it!
Source V. Hartikainen
First pattern tailor-made for Retina, with many more to come. All the old ones are upscaled, in case you want to re-download.
Source Atle Mo
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
A free background image with a seamless texture of cardboard. This texture of cardboard looks quite realistic, especially when is actually tiled.
Source V. Hartikainen
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
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
Use shift+alt+i on the selected rectangle in Inkscape to get the tile this is based on
Source Firkin
Derived from a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
From an image on opengameart.org shared by rubberduck.
Source Firkin
Same as Silver Scales, but in black. Turn your site into a dragon with this great scale pattern.
Source Alex Parker
Luxurious looking pattern (for a T-shirt maybe?) with a hint of green.
Source Simon Meek
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin