Actually remixed from a pattern on Pixabay. But then noticed a very similar one on Openclipart.org uploaded by btj51q2.
Source Firkin
This beige background pattern resembles a concrete wall with engravings or something similar to it.
Source V. Hartikainen
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
It has waves, so make sure you don’t get sea sickness.
Source CoolPatterns
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
This background pattern contains a seamless texture of bark. It's not very realistic, but I think it looks quite nice.
Source V. Hartikainen
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A repeating background with dark brown stone-like texture and abstract pattern that looks like tree trunks.
Source V. Hartikainen
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Prismatic Hypnotic Pattern No Background
Source GDJ
A seamless canvas texture for using as background on websites. Colored in pale tones of brown.
Source V. Hartikainen
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A seamless background tile of aged paper with shabby look.
Source V. Hartikainen
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
Remixed from a PNG that was uploaded to Pixabay by gingertea
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Remixed from a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Sharp pixel pattern, just like the good old days.
Source Paridhi
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857
Source Firkin