Washi (和紙?) is a type of paper made in Japan. Here’s the pattern for you!
Source Carolynne
Very simple, very blu(e). Subtle and nice.
Source Seb Jachec
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868.
Source Firkin
This is the remix of "blue wave-seigaiha".The image depicts a seamless pattern of the front upper part of Japanese five yen coin which is used currently.This design represents a rice with ripe golden ears.
Source Yamachem
A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
Sort of reminds me of those old house wallpapers.
Source Tish
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
This is so subtle: We’re talking 1% opacity. Get your squint on!
Source Atle Mo
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Prismatic Groovy Concentric Background 2
Source GDJ
Washi (和紙?) is a type of paper made in Japan. Here’s the pattern for you!
Source Carolynne
Light gray pattern with an almost wall tile-like appearance.
Source Markus Tinner
Prismatic Geometric Tessellation Pattern 3 No Background
Source GDJ
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
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
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
A seamless pattern formed from a tile made from ornament 22. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Zero CC tileable seed texture, edited by me to be seamless from a Pixabay image. CC0
Source Sojan Janso
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran