Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
Looks like an old wall. I guess that’s it then?
Source Viahorizon
Prismatic Abstract Geometric Background 4 No Black
Source GDJ
A very dark spotted twinkle pattern for your twinkle needs.
Source Badhon Ebrahim
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
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Here's a brown background pattern with subtle stripes. I hope you'll like the color. If not, feel free to change it using an image editor, if you know how of course. Personally, I'm using GIMP to create these backgrounds.
Source V. Hartikainen
A repeating background of beige (or is it more vanilla yellow) textured stripes. One more background with stripes.
Source V. Hartikainen
From a design in 'Storia del Palazzo Vecchio in Firenze', Aurelio Gotti, 1889.
Source Firkin
A seamless background tile of aged paper with shabby look.
Source V. Hartikainen
Zero CC tileable dry grass texture, photographed and made by me. CC0
Source Sojan Janso
Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Submitted as a black pattern, I made it light and a few steps more subtle.
Source Andy
A seamless texture of black leather. I think it will look best when used in headers, footers or sidebars.
Source V. Hartikainen
A very dark spotted twinkle pattern for your twinkle needs.
Source Badhon Ebrahim
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
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
Zero CC tileable ground (#2) cracked, crackled texture, made by me. CC0
Source Sojan Janso
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin