This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
This was formed by distorting an image of a background on Pixabay.
Source Firkin
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
Same classic 45-degree pattern, dark version.
Source Luke McDonald
Prismatic Isometric Cube Extra Pattern No Background
Source GDJ
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Sounds French. Some 3D square diagonals, that’s all you need to know.
Source Graphiste
Light and tiny, just the way you like it.
Source Rohit Arun Rao
A light background pattern with diagonal stripes. Here's a simple light striped background for you.
Source V. Hartikainen
Sharp diamond pattern. A small 24x18px tile.
Source Tom Neal
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
This one looks like a cork panel. Feel free to use it as a tiled background on your blog or website.
Source V. Hartikainen
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
A large pattern with funky shapes and form. An original. Sort of origami-ish.
Source Luuk van Baars
The image is a design of blue glass.How about using it as background image?
Source Yamachem
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
Prismatic Abstract Geometric Background 4
Source GDJ
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
CC0 and seamless wellington boot pattern.
Source SliverKnight
A set of paper filters. The base texture is generated the same way, only the compositing mode is varied.
Source Lazur URH