Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
The image depicts an edo-era pattern called "same-komon" or "鮫小紋"which looks like a shark skin.The "same" in Japanese means shark in English.
Source Yamachem
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
From a design in 'Storia del Palazzo Vecchio in Firenze', Aurelio Gotti, 1889.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Prismatic Triangular Background Design Mark II 5
Source GDJ
Geometric triangles seem to be quite hot these days.
Source Pixeden
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
Clean and crisp lines all over the place. Wrap it up with this one.
Source Dax Kieran
A free seamless background pattern for use on websites.
Source V. Hartikainen
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Black paper texture, based on two different images.
Source Atle Mo
Based from Design Kindle
From an image on opengameart.org shared by rubberduck.
Source Firkin
Everyone loves a diamond, right? Make your site sparkle.
Source AJ Troxell
Remixed from an image on Pixabay, the original having been uploaded by darkmoon1968.
Source Firkin
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
8 by 8 pixels, and just what the title says.
Source pixilated
Inspired by a pattern I saw in a 19th century book. This seamless pattern was created from a square tile. To get the tile, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
Diagonal lines with a lot of texture to them.
Source Ashton
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin