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
Number five from the same submitter, makes my job easy.
Source Dima Shiper
Kaleidoscope Prismatic Abstract No Background
Source GDJ
Original seamless pattern with an Inkscape filter.
Source Firkin
Here I have tried to create something that would look like maple wood. Not sure how well it's turned out, but at least it looks like wood.
Source V. Hartikainen
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
Prismatic Curved Diamond Pattern 3 No Background
Source GDJ
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868.
Source Firkin
Light and tiny, just the way you like it.
Source Rohit Arun Rao
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
The texture of this background image has some similarities with leather, and it's colored in a dark brown color. So, if you are looking for a dark brown background image for your website, this may be an option for you.
Source V. Hartikainen
A bit like smudged paint or some sort of steel, here is scribble light.
Source Tegan Male
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
A seamless texture of black leather. I think it will look best when used in headers, footers or sidebars.
Source V. Hartikainen
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
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
This one needs to be used in small areas; you can see it repeat.
Source Luca
Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin