A repeating background with wood/straw like texture.
Source V. Hartikainen
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Black And White Floral Pattern Background Inverse
Source GDJ
Prismatic Abstract Geometric Background 4
Source GDJ
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
An abstract texture of water. It's not perfect, but will do. You may download if you like it.
Source V. Hartikainen
Prismatic Geometric Pattern Background No Black
Source GDJ
First pattern tailor-made for Retina, with many more to come. All the old ones are upscaled, in case you want to re-download.
Source Atle Mo
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Has nothing to do with toast, but it’s nice and subtle.
Source Pippin Lee
No relation to the band, but damn it’s subtle!
Source Thomas Myrman
No, not the band but the pattern. Simple squares in gray tones, of course.
Source Atle Mo
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Produced using the clouds, flames and glass blocks plug-ins in Paint.net and the resulting .PNG vectorised with Vector Magic.
Source Firkin
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Could be paper, could be a Polaroid frame – up to you!
Source Chaos
ZeroCC tileable moss texture, photographed and made by me. CC0
Source Sojan Janso
From a drawing in 'Uit de geschiedenis der Heilige Stede te Amsterdam', Yohannes Sterck, 1898.
Source Firkin