Prismatic Basic Pattern 2 No Background
Source GDJ
It looks like a polished stone surface to me. Download it for free, as always.
Source V. Hartikainen
Super subtle indeed, a medium gray pattern with tiny dots in a grid.
Source Designova
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
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
Nicely crafted paper pattern, although a bit on the large side (500x593px).
Source Blaq Annabiosis
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
A seamless background pattern of dark brown wood planks.
Source V. Hartikainen
ZeroCC tileable moss texture, photographed and made by me. CC0
Source Sojan Janso
A free seamless background texture that looks like a brown stone wall.
Source V. Hartikainen
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
Greyscale version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
A free repetitive background with a dark concrete wall like texture. This one may be used in dark web site designs.
Source V. Hartikainen
Everyone loves a diamond, right? Make your site sparkle.
Source AJ Troxell
Did anyone say The Hoff? This pattern is in no way related to Baywatch.
Source Josh Green
Light and tiny, just the way you like it.
Source Rohit Arun Rao
Paper pattern with small dust particles and 45-degree strokes.
Source Atle Mo