Original minus the background
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
A yellow tiled background... Blurriness, bokeh effect and rectangles pattern in one mix.
Source V. Hartikainen
Black brick wall pattern. Brick your site up!
Source Alex Parker
Nasty or not, it’s a nice pattern that tiles. Like they all do.
Source Badhon Ebrahim
This background pattern looks like bamboo to me. Feel free to download it for your website (for your blog perhaps?).
Source V. Hartikainen
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
Use shift+alt+i on the selected rectangle in Inkscape to get the tile this is based on
Source Firkin
Prismatic Hexagonalism Pattern No Background
Source GDJ
A version without colours blended together to give a different look.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
Derived from an image that was uploaded to Pixabay by mdmelo.
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
This background pattern has futuristic look. So, maybe it could be used on websites or blogs dedicated to video games?!
Source V. Hartikainen
Prismatic Rounded Squares Grid 4 No Background
Source GDJ
Derived from a JPG that was uploaded to Pixabay by ractapopulous
Source Firkin