A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki
This is a hot one. Small, sharp and unique.
Source GraphicsWall
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
This is so subtle you need to bring your magnifier!
Source Carlos Valdez
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
I love these crisp, tiny, super subtle patterns.
Source Badhon Ebrahim
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Traced from a drawing in 'Household Stories from the Collection of the Brothers Grimm', Wilhelm Carl Grimm , 1882.
Source Firkin
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Based on an image that was uploaded to Pixabay by devanath
Source Firkin
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
This is sort of fresh, but still feels a bit old school.
Source Martuchox
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
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