A seamless background texture of old cardboard.
Source V. Hartikainen
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin
Seamless Green Tile Background
Source V. Hartikainen
A free seamless background texture of "timber wall" (colored in dark brown).
Source V. Hartikainen
Prismatic Polka Dots 3 No Background
Source GDJ
From a drawing in 'Hyde Park from Domesday-Book to date', John Ashton, 1896.
Source Firkin
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
ZeroCC tileable wood boards texture, photographed and made by me. CC0
Source Sojan Janso
A bit like smudged paint or some sort of steel, here is scribble light.
Source Tegan Male
A repeating gloomy background image. This one consists of a pattern of black chains layered on top of a dark textured background.
Source V. Hartikainen
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
A version without colours blended together to give a different look.
Source Firkin
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Remixed from a PNG that was uploaded to Pixabay by k_jprather
Source Firkin
You know I love paper patterns. Here is one from Stephen. Say thank you!
Source Stephen Gilbert
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Background formed from the original with an emboss effect.
Source Firkin
Lovely pattern with some good-looking non-random noise lines.
Source Zucx