This background pattern contains a seamless texture of bark. It's not very realistic, but I think it looks quite nice.
Source V. Hartikainen
Utilising a bird from s-light and some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A brown seamless wood texture in a form of stripe pattern. The result has turned out pretty well, in my opinion.
Source V. Hartikainen
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
Little x’es, noise and all the stuff you like. Dark like a Monday, with a hint of blue.
Source Tom McArdle
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Seamless Dark Grunge Texture. Here's a new grunge texture for use as a background.
Source V. Hartikainen
Clean and crisp lines all over the place. Wrap it up with this one.
Source Dax Kieran
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A free tileable background colored in off-white (antique white) color.
Source V. Hartikainen
The image is a design of blue glass.How about using it as background image?
Source Yamachem
Prismatic Snowflakes Pattern No Background
Source GDJ
A bit simplified version. Although it could be edited out to be simpler. Anyway, this time the tiling is converted to a pattern fill -which is using clipping for the tile's edges.
Source Lazur URH
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Square design drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
A seamlessly tileable pink background texture.
Source V. Hartikainen
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
Remix from a drawing in 'Ostatnie chwile powstania styczniowego', Zygmunt Sulima, 1887.
Source Firkin