Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Zero CC tileable cork floor, photographed and made by me. CC0
Source Sojan Janso
A white version of the very popular linen pattern.
Source Ant Ekşiler
Remixed from a JPG that was uploaded to Pixabay by theasad121
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
From an image on opengameart.org shared by rubberduck.
Source Firkin
Pattern Background, Texture, Photoshop Structure style CC0 texture.
Source Darkmoon1968
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
Super detailed 16×16 tile that forms a beautiful pattern of straws.
Source Pavel
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
Washi (和紙?) is a type of paper made in Japan. Here’s the pattern for you!
Source Carolynne
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Abstract Arbitrary Geometric Background derived from an image on Pixabay.
Source GDJ
This could be a hippy vintage wallpaper.
Source Tileable Patterns
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
Sort of reminds me of those old house wallpapers.
Source Tish
The act or state of corrugating or of being corrugated, a wrinkle; fold; furrow; ridge.
Source Anna Litvinuk
Prismatic Triangular Background Design Mark II 5
Source GDJ
A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin