Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
A free web background image with a seamless concrete-like texture and an Indian-red color.
Source V. Hartikainen
I have no idea what J Boo means by this name, but hey – it’s hot.
Source j Boo
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
Prismatic Curved Diamond Pattern 8 No Background
Source GDJ
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Alternative colour scheme for the original floral pattern.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
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
The file was named striped lens, but hey – Translucent Fibres works too.
Source Angelica
A free background pattern with abstract green tiles.
Source V. Hartikainen
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Alternative colour scheme for the original floral pattern.
Source Firkin
A seamless pattern formed from background pattern 102
Source Firkin
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
Abstract Tiled Background Extended 10
Source GDJ
Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight