Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
On a large canvas you can see it tiling, but used on smaller areas, it’s beautiful.
Source Paul Phönixweiß
Prismatic Polka Dots Mark II 3 No Background
Source GDJ
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Alternative colour scheme. 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 one needs to be used in small areas; you can see it repeat.
Source Luca
A version without colours blended together to give a different look.
Source Firkin
Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.
Source Atle Mo
Prismatic Abstract Background Design No Black
Source GDJ
As the original image 's page size is too large for its image size, I remixed it.
Source Yamachem
A simple but elegant classic. Every collection needs one of these.
Source Christopher Burton
A cute x, if you need that sort of thing.
Source Juan Scrocchi
This is a seamless pattern of regular hexagon which has a honeycomb structure.
Source Yamachem
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
This reminds me of Game Cube. A nice light 3D cube pattern.
Source Sander Ottens
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
It’s okay to be square! A nice light gray pattern with random squares.
Source Waseem Dahman
Traced from a drawing in 'Household Stories from the Collection of the Brothers Grimm', Wilhelm Carl Grimm , 1882.
Source Firkin
Different from the original in being a simple tile stored as a pattern definition, rather than numerous repeated objects. Hence easy and quick to give this pattern to objects of different shapes. To get the tile in Inkscape, select the rectangle and use shift+alt+i.
Source Firkin
Prismatic Abstract Geometric Background 2 No Black
Source GDJ