Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
It has waves, so make sure you don’t get sea sickness.
Source CoolPatterns
Lovely light gray floral motif with some subtle shades.
Source GraphicsWall
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
Actually, there's no clouds in it, but I think it looks quite nice.
Source V. Hartikainen
8 by 8 pixels, and just what the title says.
Source pixilated
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
Fix and cc0 to get the tile this is based on.
Source SliverKnight
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
This could be a hippy vintage wallpaper.
Source Tileable Patterns
A pattern drawn in Paint.net and vectorized in Inkscape.
Source Firkin
Luxurious looking pattern (for a T-shirt maybe?) with a hint of green.
Source Simon Meek
Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A seamless pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib
A seamless pattern based on a tile that can be achieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
The image depicts a seamless pattern of a fishnet with a plenty of fish.It may be a lucky charm for fishermen.
Source Yamachem
A version without colours blended together to give a different look.
Source Firkin