I skipped number 3, because it wasn’t all that great. Sorry.
Source Dima Shiper
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
Just the symbols of the signs of the zodiac distributed in a chequer board-like pattern
Source Firkin
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
Prismatic Geometric Pattern Background 2 No Black
Source GDJ
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
Submitted by DomainsInfo – wtf, right? But hey, a free pattern.
Source DomainsInfo
Black & white version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Black paper texture, based on two different images.
Source Atle Mo
Based from Design Kindle
Seamless Background For Websites. It has a texture similar to cork-board.
Source V. Hartikainen
ZeroCC tileable stone texture, edited from pixabay. CC0
Source Sojan Janso
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
Feel free to use this seamless background texture as a background on a web site. It's colored in a light pink color and is seamlessly tile-able.
Source V. Hartikainen
Scanned some rice paper and tiled it up for you. Enjoy.
Source Atle Mo
A seamless marble-like texture colored in light blue.
Source V. Hartikainen
Kaleidoscope Prismatic Abstract No Background
Source GDJ
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective