Geometric triangles seem to be quite hot these days.
Source Pixeden
A seamless pattern with wide vertical stripes colored in pale yellow.
Source V. Hartikainen
A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Similar to original, but without gaps in between the arrows. This seamless pattern was created from a rectangular tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
The act or state of corrugating or of being corrugated, a wrinkle; fold; furrow; ridge.
Source Anna Litvinuk
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Prismatic Abstract Line Art Pattern Background
Source GDJ
Background Wall, Art Abstract, Star Well & CC0 texture.
Source Ractapopulous
From a drawing in 'Uit de geschiedenis der Heilige Stede te Amsterdam', Yohannes Sterck, 1898.
Source Firkin
Colourful background achieved with gradient fills.
Source Firkin
A light gray background pattern with seamless fabric-like texture and almost unnoticeable stripes.
Source V. Hartikainen
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock