8 by 8 pixels, and just what the title says.
Source pixilated
You could get a bit dizzy from this one, but it might come in handy.
Source Dertig Media
This one needs to be used in small areas; you can see it repeat.
Source Luca
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
A bit like smudged paint or some sort of steel, here is scribble light.
Source Tegan Male
The tile this is based on was adapted from an image that was uploaded to Pixabay by frolicsomepl. It can be had in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
This is lovely, just the right amount of subtle noise, lines and textures.
Source Richard Tabor
Medium gray pattern with small strokes to give a weave effect.
Source Catherine
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A free seamless background texture of "timber wall" (colored in dark brown).
Source V. Hartikainen
A free black metallic background pattern. Here's a new pattern I made that looks metallic.
Source V. Hartikainen
From a drawing in 'Prose and Verse ', William Linton, 1836.
Source Firkin
Might not be super subtle, but quite original in its form.
Source Alex Smith
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
Prismatic Geometric Tessellation Pattern 2 No Background
Source GDJ
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Washi (和紙?) is a type of paper made in Japan. Here’s the pattern for you!
Source Carolynne
The original has been presented as black on transparent and stored in the pattern definitions. To retrieve the unit tile select the rectangle in Inkscape and use shift+alt+i
Source Firkin