Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
Prismatic Geometric Tessellation Pattern 4 No Background
Source GDJ
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Seamless Olive Green Web Background Image
Source V. Hartikainen
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
This pattern comes in orange, and it looks as if it is "made of glass".
Source V. Hartikainen
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
Scanned some rice paper and tiled it up for you. Enjoy.
Source Atle Mo
Prismatic Polyskelion Pattern No Background
Source GDJ
Seamless pattern inspired by a drawing on Pixabay. To get the tile this is formed from, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
Seamless Prismatic Quadrilateral Line Art Pattern No Background
Source GDJ
Embossed lines and squares with subtle highlights.
Source Alex Parker
Original seamless pattern with an Inkscape filter.
Source Firkin
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin