A seamless background texture of old cardboard.
Source V. Hartikainen
Inspired by a drawing seen in 'City of Liverpool', James Picton, 1883.
Source Firkin
Never out of fashion and so much hotter than the 45º everyone knows, here is a sweet 60º line pattern.
Source Atle Mo
Number 5 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Prismatic Abstract Line Art Pattern Background
Source GDJ
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A light brushed aluminum pattern for your pleasure.
Source Tim Ward
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Orange-red pattern for tiled backgrounds.
Source V. Hartikainen
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
Neat little photography icon pattern.
Source Hossam Elbialy
Prismatic Abstract Geometric Background 2
Source GDJ
Pattern Background, Texture, Photoshop Structure style CC0 texture.
Source Darkmoon1968
Actually remixed from a pattern on Pixabay. But then noticed a very similar one on Openclipart.org uploaded by btj51q2.
Source Firkin
This one is amazing, truly original. Go use it!
Source Viahorizon
A pale orange background pattern with glossy groove stripes.
Source V. Hartikainen
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Dark, crisp and subtle. Tiny black lines on top of some noise.
Source Wilmotte Bastien
Background formed from the original with an emboss effect
Source GDJ