A seamlessly repeating background pattern of wood. The image is procedurally generated, and, I think, it's turned out quite well.
Source V. Hartikainen
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
Prismatic Groovy Concentric Background 5
Source GDJ
Prismatic Rounded Squares Grid 4 No Background
Source GDJ
A seamless paper background colored in pale yellow.
Source V. Hartikainen
A background tile of dark textile. Made this a long time ago and just now decided to publish it.
Source V. Hartikainen
From a drawing in 'Uit de geschiedenis der Heilige Stede te Amsterdam', Yohannes Sterck, 1898.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
This one looks like a cork panel. Feel free to use it as a tiled background on your blog or website.
Source V. Hartikainen
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
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
You guessed it – looks a bit like cloth.
Source Peax Webdesign
The tile this is formed from can be retrieved in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
Nasty or not, it’s a nice pattern that tiles. Like they all do.
Source Badhon Ebrahim
A seamless pattern formed from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Just what the name says, paper fibers. Always good to have.
Source Heliodor jalba
Remixed from a drawing in 'Jezebel's Daughter', Wilkie Collins 1880
Source Firkin
Remixed from a drawing in 'A Child of the Age', Francis Adams, 1894.
Source Firkin