8 by 8 pixels, and just what the title says.
Source pixilated
This is the remix of "polka dot seamless pattern".The image depicts polka dot seamless pattern.
Source Yamachem
A seamless tessellation pattern. To get the tile this is formed from, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This is a remix of "blue wave-seigaiha".I hope this subtle color version of Seigaiha would be suitable for background .
Source Yamachem
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
A free seamless background texture that looks like a brown stone wall.
Source V. Hartikainen
A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.
Source Firkin
A seamless background pattern with a texture of wood planks. This wood background pattern has vertically arranged planks. You may try to rotate it 90°, to see how it will look like when the wood planks are arranged horizontally.
Source V. Hartikainen
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
Light gray paper pattern with small traces of fiber and some dust.
Source Atle Mo
Semi-light fabric pattern made out of random pixels in shades of gray.
Source Atle Mo
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
This one is super crisp at 2X. Lined paper with some dust and scratches.
Source HQvectors
You know, tiny and sharp. I’m sure you’ll find a use for it.
Source Atle Mo
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
A seamless background pattern with impressed gray dots.
Source V. Hartikainen
A free background pattern with abstract green tiles.
Source V. Hartikainen
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