Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
A pattern drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
This background texture resembles stone. It may be used as a background on web pages or on some of their html elements (header, borders, menu bar, etc.). Just modify it for your needs.
Source V. Hartikainen
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
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
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
Hey, you never know when you’ll need a bird pattern, right?
Source Pete Fecteau
Prismatic Groovy Concentric Background 3
Source GDJ
This one looks like a cork panel. Feel free to use it as a tiled background on your blog or website.
Source V. Hartikainen
A seamless pattern formed from cross 4. To get the original tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Abstract Tiled Background Extended 12
Source GDJ
Seamless pattern inspired by a drawing on Pixabay. To get the tile this is formed from, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
An attempt for cleaning up the original image in a few steps.
Source Lazur URH
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
From a drawing in 'Codogno e il suo territorio nella cronaca e nella storia'', Gio and Giarella Cairo, 1897.
Source Firkin
Nicely executed tiling for an interesting pattern.
Source Ignasi Àvila Padró
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
Derived from an image that was uploaded to Pixabay by mdmelo.
Source Firkin
Heavily remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Inspired by a drawing in 'Kulturgeschichte', Freidrich Hellwald, 1896.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
You know I love paper patterns. Here is one from Stephen. Say thank you!
Source Stephen Gilbert