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
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Kaleidoscope Prismatic Abstract No Background
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
Another fairly simple design drawn in Paint.net and vectorized in Inkscape.
Source Firkin
The image depicts a seamless pattern made using a bird's face.
Source Yamachem
Tiny circle waves, almost like the ocean.
Source Sagive
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Nothing like a clean set of bed sheets, huh?
Source Badhon Ebrahim
Nasty or not, it’s a nice pattern that tiles. Like they all do.
Source Badhon Ebrahim
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
Adapted from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Awesome name, great pattern. Who does not love space?
Source Nick Batchelor
Prismatic 3D Isometric Tessellation Pattern 6
Source GDJ
Dark, crisp and subtle. Tiny black lines on top of some noise.
Source Wilmotte Bastien
Derived from a JPG that was uploaded to Pixabay by ractapopulous
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen