Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
From a drawing in 'Uit de geschiedenis der Heilige Stede te Amsterdam', Yohannes Sterck, 1898.
Source Firkin
I love these crisp, tiny, super subtle patterns.
Source Badhon Ebrahim
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
A cute x, if you need that sort of thing.
Source Juan Scrocchi
Prismatic Curved Diamond Pattern 6 No Background
Source GDJ
Remixed from a vector adapted from a jpg on Pixabay. The tile this is constructed from can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Prismatic Geometric Pattern Background
Source GDJ
Sort of like the Photoshop transparent background, but better!
Source Alex Parker
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay
Has nothing to do with toast, but it’s nice and subtle.
Source Pippin Lee
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i
Source Firkin
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
Zero CC tileable pine bark texture, photographed and made by me. CC0
Source Sojan Janso
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
A dark background pattern/texture of a dimpled metal plate.
Source V. Hartikainen
U.S.-based National Fire Protection Association standard fire diamond for flagging risks posed by hazardous materials. The red diamond has a number 0-4 depending on flammability. The blue diamond has a number 0-4 depending on health hazard. The yellow has a number 0-4 depending on reactivity. the white square has a special notice, e.g OX for oxidizer.
Source Firkin