Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile
I love these crisp, tiny, super subtle patterns.
Source Badhon Ebrahim
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Abstract Geometric Background 5
Source GDJ
Awesome name, great pattern. Who does not love space?
Source Nick Batchelor
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
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 a tile made from ornament 22. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
An abstract texture of black metal pipes (seamless).
Source V. Hartikainen
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin
Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Prismatic Curved Diamond Pattern 3 No Background
Source GDJ
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
Sort of reminds me of those old house wallpapers.
Source Tish
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using 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
I took the liberty of using Dmitry’s pattern and made a version without perforation.
Source Atle Mo