Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
The original enhanced with one of Inkscapes's filters.
Source Firkin
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
A seamless pattern formed from background pattern 102
Source Firkin
Derived from an image that was uploaded to Pixabay by mdmelo.
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
Colorful Floral Background 3 No Black
Source GDJ
ZeroCC tileable moss texture, photographed and made by me. CC0
Source Sojan Janso
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Prismatic Curved Diamond Pattern 7 No Background
Source GDJ
This one has rusty dark brown texture.
Source V. Hartikainen
This ons is quite old school looking. Retro, even. I like it.
Source Arno Declercq
Heavily remixed from a drawing in 'Barbara Leybourne; a story of eighty years ago', Sarah Hamer, 1889.
Source Firkin
Prismatic Abstract Background Design No Black
Source GDJ
I took the liberty of using Dmitry’s pattern and made a version without perforation.
Source Atle Mo
The image depicts a seamless pattern which includes hexagonally-aligned gourds with BG in light-brown.
Source Yamachem
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Prismatic Basic Pattern 2 No Background
Source GDJ
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Remixed from a drawing in 'A Child of the Age', Francis Adams, 1894.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
This is the remix of an Openclipart clipart called "Maze" uploaded by "any_ono_mous".Thanks.This is a seamless pattern of a maze.
Source Yamachem
I asked Gjermund if he could make a pattern for us – result!
Source Gjermund Gustavsen
Prismatic Polka Dots Mark II 3 No Background
Source GDJ