8 by 8 pixels, and just what the title says.
Source pixilated
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
A dark pattern made out of 3×3 circles and a 1px shadow. This works well as a carbon texture or background.
Source Atle Mo
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
This one is amazing, truly original. Go use it!
Source Viahorizon
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
You know I love paper patterns. Here is one from Stephen. Say thank you!
Source Stephen Gilbert
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
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
Fix and cc0 to get the tile this is based on.
Source SliverKnight
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857
Source Firkin
Background formed from the original with an emboss effect.
Source Firkin
Smooth Polaroid pattern with a light blue tint.
Source Daniel Beaton
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Colour version of the original pattern.
Source Firkin
This could be a hippy vintage wallpaper.
Source Tileable Patterns
This one is amazing, truly original. Go use it!
Source Viahorizon