After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
A seamlessly tileable pink background texture.
Source V. Hartikainen
Alternative colour scheme for the original floral pattern.
Source Firkin
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Remixed from a drawing in 'Line and form", Walter Crane, 1914.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
That’s what it is, a dark dot. Or sort of carbon looking.
Source Tsvetelin Nikolov
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
This could be a hippy vintage wallpaper.
Source Tileable Patterns
A grayscale fabric pattern with vertical lines of stitch holes.
Source V. Hartikainen
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
A brown seamless wood texture in a form of stripe pattern. The result has turned out pretty well, in my opinion.
Source V. Hartikainen
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
Prismatic Abstract Background Design
Source GDJ
Zero CC tileable grass texture, photographed and made by me. CC0
Source Sojan Janso
From a drawing in 'Az Osztrák-Magyar Monarchia irásban és képben', 1885.
Source Firkin
If you need a green background for your blog/website, try this one. Remember that Green Striped Background is seamlessly tileable.
Source V. Hartikainen
Prismatic Groovy Concentric Background
Source GDJ
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin