This one is something special. I’d call it a flat pattern, too. Very well done, sir!
Source GetDiscount
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
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
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
This one needs to be used in small areas; you can see it repeat.
Source Luca
Prismatic Groovy Concentric Background 4
Source GDJ
Background Wall, Art Abstract, white Well & CC0 texture.
Source Ractapopulous
A bit strange this one, but nice at the same time.
Source Diogo Silva
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Square design drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
Black And White Floral Pattern Background from PDP.
Source GDJ
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Inspired by a JPG that was uploaded to Pixabay by kokon_art
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo
Has nothing to do with toast, but it’s nice and subtle.
Source Pippin Lee
Used in small doses, this could be a nice subtle pattern. Used on a large surface, it’s dirty!
Source Paul Reulat