A bit strange this one, but nice at the same time.
Source Diogo Silva
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
Might not be super subtle, but quite original in its form.
Source Alex Smith
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
Prismatic Curved Diamond Pattern No Background
Source GDJ
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
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
A seamless pattern created from a square tile. To get the tile, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
A very dark spotted twinkle pattern for your twinkle needs.
Source Badhon Ebrahim
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'Jardyne's Wife', Charles Wills, 1891.
Source Firkin
Sort of like the Photoshop transparent background, but better!
Source Alex Parker
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Geometric Tessellation Pattern 2 No Background
Source GDJ
Prismatic Groovy Concentric Background 4
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A heavy hitter at 400x400px, but lovely still.
Source Breezi
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin