Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
Non-seamless pattern drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Might not be super subtle, but quite original in its form.
Source Alex Smith
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Submitted as a black pattern, I made it light and a few steps more subtle.
Source Andy
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
The image depicts the Japanese Edo pattern called "seigaiha" or "青海波" meaning "blue -sea- wave".I hope it's suitable for the summer season.
Source Yamachem
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
You just can’t get enough of the fabric patterns, so here is one more for your collection.
Source Krisp Designs
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
The name Paisley reminds me of an old British servant. That’s just me.
Source Swetha
From a drawing in 'Danmarks Riges Historie af J. Steenstrup, Kr. Erslev, A. Heise, V. Mollerup, J. A. Fridericia, E. Holm, A. D. Jørgensen', 1897.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
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
This is the remix of "polka dot seamless pattern".The image depicts polka dot seamless pattern.
Source Yamachem
Sharp pixel pattern, just like the good old days.
Source Paridhi
Traced from a drawing in 'Household Stories from the Collection of the Brothers Grimm', Wilhelm Carl Grimm , 1882.
Source Firkin
More leather, and this time it’s bigger! You know, in case you need that.
Source Elemis
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Prismatic Groovy Concentric Background 5 No Black
Source GDJ