Sounds French. Some 3D square diagonals, that’s all you need to know.
Source Graphiste
Derived from a drawing in 'Elfrica. An historical romance of the twelfth century', Charlotte Boger, 1885
Source Firkin
The original enhanced with one of Inkscapes's filters.
Source Firkin
Prismatic Hexagonalist Pattern No Background
Source GDJ
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Pattern Background, Texture, Photoshop Structure style CC0 texture.
Source Darkmoon1968
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
An emulated “transparent” background pattern, like that of all kinds of computer graphics software.
Source AdamStanislav
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
A simple bump filter made upon request at irc #inkscape at freenode. Made a screen capture of the making here: https://youtu.be/TGAWYKVLxQw
Source Lazur URH
This is so subtle you need to bring your magnifier!
Source Carlos Valdez
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
The image is a design of blue glass.How about using it as background image?
Source Yamachem
Prismatic Geometric Pattern Background 2 No Black
Source GDJ
A bit strange this one, but nice at the same time.
Source Diogo Silva
Paper model of a tetrahedron. Modelo de papel de um tetraedro.
Source laobc
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Black brick wall pattern. Brick your site up!
Source Alex Parker
A simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib
Nothing like a clean set of bed sheets, huh?
Source Badhon Ebrahim
Smooth Polaroid pattern with a light blue tint.
Source Daniel Beaton