CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A seamless design of flowers remixed from a jpg on Pixabay by Prawny.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
A large pattern with funky shapes and form. An original. Sort of origami-ish.
Source Luuk van Baars
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
White handmade paper pattern with small bumps.
Source Marquis
More in the paper realm, this time with fibers.
Source Jorge Fuentes
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
Old China with a modern twist, take two.
Source Adam Charlts
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
Prismatic Polka Dots Mark II 3 No Background
Source GDJ
This reminds me of Game Cube. A nice light 3D cube pattern.
Source Sander Ottens
This is a hot one. Small, sharp and unique.
Source GraphicsWall
It has waves, so make sure you don’t get sea sickness.
Source CoolPatterns
Zero CC tileable wood texture, made by me procedurally in Neo Texture Edit.
Source Sojan Janso