The image depicts meshed silhouettes of various things.The original image is an OCAL clipart called "Enter FOSSASIA 2016 #IoT T-shirt Design Contest" uploaded by "openclipart".Thanks.
Source Yamachem
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
Prismatic Abstract Geometric Background 4
Source GDJ
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
Could be paper, could be a Polaroid frame – up to you!
Source Chaos
Prismatic Abstract Geometric Background 5
Source GDJ
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
You know I’m a sucker for these. Well-crafted paper pattern.
Source Mihaela Hinayon
Square design drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
Retro Circles Background 7 No Black
Source GDJ
Zero CC tileable dry grass texture, photographed and made by me. CC0
Source Sojan Janso
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin