Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
I asked Gjermund if he could make a pattern for us – result!
Source Gjermund Gustavsen
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
From a drawing in 'Az Osztrák-Magyar Monarchia irásban és képben', 1885.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A beautiful dark wood pattern, superbly tiled.
Source Omar Alvarado
Colour version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Prismatic Basic Pattern 2 No Background
Source GDJ
Dark, crisp and subtle. Tiny black lines on top of some noise.
Source Wilmotte Bastien
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Used the 6th circle pattern designed by Viscious-Speed to create a print that can be used for card making or scrapbooking. Save as a PDF file for the best printing option.
Source Lovinglf
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
On a large canvas you can see it tiling, but used on smaller areas, it’s beautiful.
Source Paul Phönixweiß
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin