This could be a hippy vintage wallpaper.
Source Tileable Patterns
Prismatic Abstract Geometric Background 4
Source GDJ
Prismatic Geometric Pattern Background
Source GDJ
Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
The image is a seamless pattern of a fishnet.
Source Yamachem
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A free seamless background pattern for use on websites.
Source V. Hartikainen
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
Paper model of a tetrahedron. Modelo de papel de um tetraedro.
Source laobc
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
These dots are already worn for you, so you don’t have to.
Source Matt McDaniel
Not the Rebel alliance, but a dark textured pattern.
Source Hendrik Lammers
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
A seamless pattern of dark bricks. Maybe it's not very realistic, but it looks good in my opinion.
Source V. Hartikainen
Based on an image that was uploaded to Pixabay by devanath
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
From a drawing in 'Hundert Jahre in Wort und Bild', S. Stefan, 1899.
Source Firkin
Submitted by DomainsInfo – wtf, right? But hey, a free pattern.
Source DomainsInfo