The image depicts polka dot seamless pattern.
Source Yamachem
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin
Zero CC tileable ground cracked, crackled, texture, made by me.
Source Sojan Janso
From a drawing in 'Bond Slaves. The story of a struggle.', Isabella Varley, 1893.
Source Firkin
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
From a drawing in 'Hubert Montreuil, or the Huguenot and the Dragoon', Francisca Ouvry, 1873.
Source Firkin
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
A seamless background texture of old cardboard.
Source V. Hartikainen
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
This background pattern contains a seamless texture of bark. It's not very realistic, but I think it looks quite nice.
Source V. Hartikainen
Embossed lines and squares with subtle highlights.
Source Alex Parker
Remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
A colourful background drawn originally in paint.net and vectorised in Vector Magic.
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
This one is something special. I’d call it a flat pattern, too. Very well done, sir!
Source GetDiscount