Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Continuing the geometric trend, here is one more.
Source Mike Warner
Original minus the background
Source Firkin
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Prismatic Triangular Background Design Mark II 5
Source GDJ
Prismatic Groovy Concentric Background No Black
Source GDJ
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
Inspired by a pattern I saw in a 19th century book. This seamless pattern was created from a square tile. To get the tile, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
From a drawing in 'Friend or Fortune? The story of a strange year', Robert Overton, 1897.
Source Firkin
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
More bright luxury. This is a bit larger than fancy deboss, and with a bit more noise.
Source Viszt Péter
This beige background pattern resembles a concrete wall with engravings or something similar to it.
Source V. Hartikainen
Dark blue concrete wall with some small dust spots.
Source Atle Mo
A seamlessly tileable pink background texture.
Source V. Hartikainen
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Might not be super subtle, but quite original in its form.
Source Alex Smith