Small dots with minor circles spread across to form a nice mosaic.
Source John Burks
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
Prismatic Hexagonalist Pattern No Background
Source GDJ
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
Sometimes you just need the simplest thing.
Source Fabricio
Might not be super subtle, but quite original in its form.
Source Alex Smith
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
An orange vertically striped background pattern. Feel free to download and use this orange background pattern, for example, on the web). It resembles a wallpaper with vertical stripes or something similar to it.
Source V. Hartikainen
Hey, you never know when you’ll need a bird pattern, right?
Source Pete Fecteau
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Colourful background achieved with gradient fills.
Source Firkin
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
Geometric triangles seem to be quite hot these days.
Source Pixeden
Alternative colour scheme. 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
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Formed by distorting an image on Pixabay that was uploaded by gustavorezende. To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
Remixed from a drawing in 'Line and form", Walter Crane, 1914.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett