A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868.
Source Firkin
Here's a seamless brown cork board background texture. Feel free to download or reshare if you like.
Source V. Hartikainen
Colour version of the original pattern inspired by the front cover of 'Old and New Paris', Henry Edwards, 1894.
Source Firkin
Vertical lines with a bumpy, yet crisp, feel to it.
Source Raasa
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
Remixed from an image that was uploaded to Pixabay by CatherineClennan
Source Firkin
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
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
Tile-able Dark Brown Wood Background. Feel free to use it as a background image in your designs or somewhere on the web. By the way, the color seems to be close to Coffee Brown.
Source V. Hartikainen
Here's a brown background pattern with subtle stripes. I hope you'll like the color. If not, feel free to change it using an image editor, if you know how of course. Personally, I'm using GIMP to create these backgrounds.
Source V. Hartikainen
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
Prismatic Hypnotic Pattern No Background
Source GDJ
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
A pale olive green background with a seamless texture.
Source V. Hartikainen
A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Dark wooden pattern, given the subtle treatment. based on texture from Cloaks.
Same classic 45-degree pattern, dark version.
Source Luke McDonald
Little x’es, noise and all the stuff you like. Dark like a Monday, with a hint of blue.
Source Tom McArdle