This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
Black And White Floral Pattern Background Inverse
Source GDJ
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
Dark blue concrete wall with some small dust spots.
Source Atle Mo
A seamlessly repeating background pattern of wood. The image is procedurally generated, and, I think, it's turned out quite well.
Source V. Hartikainen
From drawing in 'Musings in Maoriland', Thomas Bracken, 1890.
Source Firkin
Prismatic Hexagonalism Pattern No Background
Source GDJ
Prismatic Abstract Geometric Background 2 No Black
Source GDJ
High detail stone wall with minor cracks and specks.
Source Projecteightyfive
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
Background Wall, Art Abstract, Star Well & CC0 texture.
Source Ractapopulous
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Prismatic Snowflakes Pattern No Background
Source GDJ
Remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed