The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
New paper pattern with a slightly organic feel to it, using some thin threads.
Source Atle Mo
A criss-cross pattern similar to one I saw mown into a sports field.
Source Firkin
Zero CC tileable yellow craft paper; scanned and made by me. CC0
Source Sojan Janso
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Here's a new paper-like background for free use on personal and commercial projects (this applies to all background patterns here).
Source V. Hartikainen
Everyone loves a diamond, right? Make your site sparkle.
Source AJ Troxell
A seamless pattern formed from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
Here's a bluish gray striped background pattern for use on web sites.
Source V. Hartikainen
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
I took the liberty of using Dmitry’s pattern and made a version without perforation.
Source Atle Mo
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
Prismatic Hypnotic Pattern No Background
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Geometric triangles seem to be quite hot these days.
Source Pixeden
A seamless pattern based on a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin