Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Remixed from a drawing in 'An Index to Deering's Nottinghamia Vetus et Nova', Rupert Chicken, 1899. The unit tile can be had by selecting the rectangle in Inkscape and using shift-alt-i
Source Firkin
A free pink background pattern.
Source V. Hartikainen
Nasty or not, it’s a nice pattern that tiles. Like they all do.
Source Badhon Ebrahim
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Light gray grunge wall with a nice texture overlay.
Source Adam Anlauf
A dark brown fabric-like background texture with seamless pattern of winding stripes.
Source V. Hartikainen
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
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
Nasty or not, it’s a nice pattern that tiles. Like they all do.
Source Badhon Ebrahim
Washi (和紙?) is a type of paper made in Japan. Here’s the pattern for you!
Source Carolynne
Prismatic Rounded Squares Grid 4 No Background
Source GDJ
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
Carbon fiber is never out of fashion, so here is one more style for you.
Source Alfred Lee
From a drawing in 'Handbook of the excursions proposed to be made by the Lincoln Diocesan Architectural Society, on the 27th and 28th of May, 1857', Edward Trollope, 1857.
Source Firkin
Same as Silver Scales, but in black. Turn your site into a dragon with this great scale pattern.
Source Alex Parker
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Prismatic Geometric Pattern Background 2 No Black
Source GDJ
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
Number 4 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
Prismatic Abstract Geometric Background 4 No Black
Source GDJ
This one is something special. I’d call it a flat pattern, too. Very well done, sir!
Source GetDiscount
Retro Circles Background 4 No Black
Source GDJ
This was formed by distorting an image of a background on Pixabay.
Source Firkin