A seamless pattern formed from a square tile. The tile 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
Derived from an image that was uploaded to Pixabay by mdmelo.
Source Firkin
Derived from an image that was uploaded to Pixabay by darkmoon1968
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Love the style on this one, very fresh. Diagonal diamond pattern. Get it?
Source INS
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
These dots are already worn for you, so you don’t have to.
Source Matt McDaniel
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
Not sure if this is related to the Nami you get in Google image search, but hey, it’s nice!
Source Dertig Media
Zero CC tileable yellow craft paper; scanned and made by me. CC0
Source Sojan Janso
Scanned some rice paper and tiled it up for you. Enjoy.
Source Atle Mo
Kaleidoscope Prismatic Abstract No Background
Source GDJ
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
This seamless pattern consists of a blue grid on a yellow background.
Source V. Hartikainen
Not so subtle. These tileable wood patterns are very useful.
Source Elemis
Fix side and a seamless pattern formed from circles.
Source SliverKnight
From a drawing in 'Codogno e il suo territorio nella cronaca e nella storia'', Gio and Giarella Cairo, 1897.
Source Firkin
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ