Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Here's a camo print with more tan and less green, such as might be used in a desert scenario. This is tileable, so it can be used as a wallpaper or background.
Source Eady
Super detailed 16×16 tile that forms a beautiful pattern of straws.
Source Pavel
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
A seamless pattern formed from a rectangular tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Adapted from an image that was uploaded to Pixabay by Anerma.
Source Firkin
Prismatic Geometric Pattern Background No Black
Source GDJ
Dark pattern with some nice diagonal stitched lines crossing over.
Source Ashton
Background Wall, Art Abstract, Watercolor Vintage style CC0 texture.
Source Ractapopulous
Very simple, very blu(e). Subtle and nice.
Source Seb Jachec
Prismatic Polka Dots Mark II No Background
Source GDJ
Zero CC tileable grass texture, photographed and made by me. CC0
Source Sojan Janso
Inspired by a pattern I saw in a 19th century book. This seamless pattern was created from a square tile. To get the tile, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
If you don’t like cream and pixels, you’re in the wrong place.
Source Mizanur Rahman
Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
This background pattern has futuristic look. So, maybe it could be used on websites or blogs dedicated to video games?!
Source V. Hartikainen
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
One can never have too few rice paper patterns, so here is one more.
Source Atle Mo
Semi-light fabric pattern made out of random pixels in shades of gray.
Source Atle Mo