A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Prismatic Hypnotic Pattern 2 No Background
Source GDJ
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Prismatic Triangular Background Design Mark II 5
Source GDJ
If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
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
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
Number 2 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Remixed from a drawing in 'Prehistoric Man: researches into the origin of civilisation in the old and the new world', Daniel Wilson, 1876.
Source Firkin
Smooth Polaroid pattern with a light blue tint.
Source Daniel Beaton
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
From a drawing in 'Worsborough; its historical associations and rural attractions', Joseph Wilkinson, 1879.
Source Firkin
Orange-red pattern for tiled backgrounds.
Source V. Hartikainen
Lovely light gray floral motif with some subtle shades.
Source GraphicsWall
Seamless Green Tile Background
Source V. Hartikainen
Inspired by a 1930s wallpaper pattern I saw on TV.
Source Firkin