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
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
From a drawing in 'Hundert Jahre in Wort und Bild', S. Stefan, 1899.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Remixed from a vector adapted from a jpg on Pixabay. The tile this is constructed from can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Vertical lines with a bumpy, yet crisp, feel to it.
Source Raasa
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
Remixed from a drawing in 'Incidents on a Journey through Nubia to Darfoor', F. Ensor, 1891.
Source Firkin
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski
Prismatic Polka Dots Mark II 3 No Background
Source GDJ
This one has rusty dark brown texture.
Source V. Hartikainen
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
That’s what it is, a dark dot. Or sort of carbon looking.
Source Tsvetelin Nikolov
Remixed from a drawing in 'Kulturgeschichte der Deutschen im Mittelalter' Franz von Loeher, 1891. The unit tile can be had by selecting the rectangle in Inkscape and using shift-alt-i
Source Firkin