Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Produced using the clouds, flames and glass blocks plug-ins in Paint.net and the resulting .PNG vectorised with Vector Magic.
Source Firkin
Number 2 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Prismatic Abstract Geometric Background 4 No Black
Source GDJ
Plywood Web Background background image for use in web design.
Source V. Hartikainen
Just like the black maze, only in light gray. Duh.
Source Peax
Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
This seamless light brown background texture resembles a wallpaper with vertical stripes. One way to use it is as a tiled background on web sites.
Source V. Hartikainen
Paper pattern with small dust particles and 45-degree strokes.
Source Atle Mo
A light background pattern with diagonal stripes. Here's a simple light striped background for you.
Source V. Hartikainen
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
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Greyscale version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A repeating background of thick textured paper. Actually, it turned out to look like something between a paper and fabric.
Source V. Hartikainen
Remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
Prismatic Floral Background No Black
Source GDJ
An alternative colour scheme for the original seamless texture formed from an image on Pixabay.
Source Firkin