Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
A comeback for you: the popular Escheresque, now in black.
Source Patten
Sharp but soft triangles in light shades of gray.
Source Pixeden
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From an image on opengameart.org shared by rubberduck.
Source Firkin
Prismatic Groovy Concentric Background 2
Source GDJ
Actually, there's no clouds in it, but I think it looks quite nice.
Source V. Hartikainen
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
One more sharp little tile for you. Subtle circles this time.
Source Blunia
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
A free grid paper background pattern for using on web sites.
Source V. Hartikainen
Just what the name says, paper fibers. Always good to have.
Source Heliodor jalba
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
A white version of the very popular linen pattern.
Source Ant Ekşiler
From a drawing in 'Cowdray: the history of a great English House', Julia Roundell, 1884.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A light gray wall or floor (you decide) of concrete.
Source Atle Mo