Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Non-seamless pattern drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
The image is a seamless pattern of a fishnet.
Source Yamachem
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Dark pattern with some nice diagonal stitched lines crossing over.
Source Ashton
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A background tile of dark textile. Made this a long time ago and just now decided to publish it.
Source V. Hartikainen
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
From drawing in 'Musings in Maoriland', Thomas Bracken, 1890.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Prismatic Polka Dots Mark II 2 No Background
Source GDJ
A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
A classic dark tile for a bit of vintage darkness.
Source Listvetra
Here's a seamless brown cork board background texture. Feel free to download or reshare if you like.
Source V. Hartikainen
This is so subtle: We’re talking 1% opacity. Get your squint on!
Source Atle Mo
Pattern formed from simple shapes. Black version.
Source Firkin
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
Dark and hard, just the way we like it. Embossed triangles makes a nice pattern.
Source Ivan Ginev