A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Just like the black maze, only in light gray. Duh.
Source Peax
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki
Your eyes can trip a bit from looking at this – use it wisely.
Source Michal Chovanec
Here's a seamless brown cork board background texture. Feel free to download or reshare if you like.
Source V. Hartikainen
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
The following orange background pattern resembles a honeycomb.
Source V. Hartikainen
Has nothing to do with toast, but it’s nice and subtle.
Source Pippin Lee
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This is so subtle: We’re talking 1% opacity. Get your squint on!
Source Atle Mo
Black & white version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin