Never out of fashion and so much hotter than the 45º everyone knows, here is a sweet 60º line pattern.
Source Atle Mo
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin
Prismatic Triangular Background Design Mark II 5
Source GDJ
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
Prismatic Floral Background No Black
Source GDJ
The file was named striped lens, but hey – Translucent Fibres works too.
Source Angelica
Utilising a bird from s-light and some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
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
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
From a drawing in 'Hundert Jahre in Wort und Bild', S. Stefan, 1899.
Source Firkin
From a drawing in 'Bond Slaves. The story of a struggle.', Isabella Varley, 1893.
Source Firkin
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i
Source Firkin
Psychedelic Geometric Background No Black
Source GDJ
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
A heavy hitter at 400x400px, but lovely still.
Source Breezi
An alternative colour scheme to the original seamless pattern.
Source Firkin
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
A cute x, if you need that sort of thing.
Source Juan Scrocchi
A new one called white wall, not by me this time.
Source Yuji Honzawa
A bit strange this one, but nice at the same time.
Source Diogo Silva