Not so subtle. These tileable wood patterns are very useful.
Source Elemis
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
This background pattern has futuristic look. So, maybe it could be used on websites or blogs dedicated to video games?!
Source V. Hartikainen
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Prismatic Curved Diamond Pattern 3 No Background
Source GDJ
Colour version of the original seamless pattern.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Pattern formed from simple shapes. Black version.
Source Firkin
This could be a hippy vintage wallpaper.
Source Tileable Patterns
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Greyscale version of a pattern that came out of playing with the 'slinky' plug-in for Paint.net
Source Firkin
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
Stefan is hard at work, this time with a funky pattern of squares.
Source Stefan Aleksić
A seamless pattern created from a square tile. To get the tile, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
U.S.-based National Fire Protection Association standard fire diamond for flagging risks posed by hazardous materials. The red diamond has a number 0-4 depending on flammability. The blue diamond has a number 0-4 depending on health hazard. The yellow has a number 0-4 depending on reactivity. the white square has a special notice, e.g OX for oxidizer.
Source Firkin
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Washi (和紙?) is a type of paper made in Japan. Here’s the pattern for you!
Source Carolynne
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
Derived from a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
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 light background pattern with diagonal stripes. Here's a simple light striped background for you.
Source V. Hartikainen