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
Little x’es, noise and all the stuff you like. Dark like a Monday, with a hint of blue.
Source Tom McArdle
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Seamless pattern inspired by a drawing on Pixabay. To get the tile this is formed from, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Orange-red pattern for tiled backgrounds.
Source V. Hartikainen
A free seamless background image with abstract texture of green "curtain".
Source V. Hartikainen
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
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
This is the remix of "plant pattern 02".I changed the object color to white and the BG to purple.The image a seamless pattern derived from a weed which I can't identify.The original weed image is from here:jp.pinterest.com/pin/500744052301423641/
Source Yamachem
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Small dots with minor circles spread across to form a nice mosaic.
Source John Burks
Remixed from a drawing in 'A Child of the Age', Francis Adams, 1894.
Source Firkin
Light honeycomb pattern made up of the classic hexagon shape.
Source Federica Pelzel
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
This is so subtle you need to bring your magnifier!
Source Carlos Valdez
A pale yellow background pattern with vertical stripes. The stripes are partially faded. I think this background image turned out pretty well, especially those faded stripes.
Source V. Hartikainen
Remixed from a PNG that was uploaded to Pixabay by VictorianLady
Source Firkin
Black brick wall pattern. Brick your site up!
Source Alex Parker
Prismatic Groovy Concentric Background
Source GDJ
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin