If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
Prismatic Curved Diamond Pattern 6 No Background
Source GDJ
A lovely light gray pattern with stripes and a dash of noise.
Source V. Hartikainen
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Dead simple but beautiful horizontal line pattern.
Source Fabian Schultz
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Background Wall, Art Abstract, Watercolor Vintage style CC0 texture.
Source Ractapopulous
This one is amazing, truly original. Go use it!
Source Viahorizon
A free seamless background texture of "timber wall" (colored in dark brown).
Source V. Hartikainen
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A free light orange brown wallpaper with vertical stripes designed for use as a tiled background on websites. An yet another background pattern with vertical stripes.
Source V. Hartikainen
Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
Different from the original in being a simple tile stored as a pattern definition, rather than numerous repeated objects. Hence easy and quick to give this pattern to objects of different shapes. To get the tile in Inkscape, select the rectangle and use shift+alt+i.
Source Firkin
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
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Derived from a drawing in 'Elfrica. An historical romance of the twelfth century', Charlotte Boger, 1885
Source Firkin
Paper model of a tetrahedron. Modelo de papel de um tetraedro.
Source laobc
ZeroCC tileable beechwood wood texture, generated in Neo Texture Edit by me. CC0
Source Sojan Janso
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A nice one indeed, but I have a feeling we have it already? If you spot a copy, let me know on Twitter.
Source Graphiste
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin