This beige background pattern resembles a concrete wall with engravings or something similar to it.
Source V. Hartikainen
Use shift+alt+i on the selected rectangle in Inkscape to get the tile this is based on
Source Firkin
Prismatic Groovy Concentric Background 2
Source GDJ
Just the symbols of the signs of the zodiac distributed in a chequer board-like pattern
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Zero CC Mossy stone tileable texture, photographed and made by me. CC0
Source Sojan Janso
Sort of reminds me of those old house wallpapers.
Source Tish
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
Zero CC tileable ground cracked, crackled, texture, made by me.
Source Sojan Janso
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.
Source Firkin
If you’re sick of the fancy 3D, grunge and noisy patterns, take a look at this flat 2D brick wall.
Source Listvetra
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
A very dark spotted twinkle pattern for your twinkle needs.
Source Badhon Ebrahim
Colorful Floral Background No Black
Source GDJ
A free seamless background image with abstract texture of green "curtain".
Source V. Hartikainen
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
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers