The following repeating website background is colored in a blue gray color and resembles a concrete wall or something similar to it.
Source V. Hartikainen
This is the remix of "Background pattern 115" uploaded by "Firkin".Thanks.
Source Yamachem
Greyscale version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
Some dark 45 degree angles creating a nice pattern. Huge.
Source Dark Sharp Edges
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
A simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
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
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Same as Silver Scales, but in black. Turn your site into a dragon with this great scale pattern.
Source Alex Parker
A light gray background pattern with seamless fabric-like texture and almost unnoticeable stripes.
Source V. Hartikainen
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
Remixed from a drawing in 'Paul's Sister', Frances Peard, 1889.
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
This background pattern contains a texture of yellow wood planks. I think it looks quite original.
Source V. Hartikainen
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
Just what the name says, paper fibers. Always good to have.
Source Heliodor jalba
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin