Your eyes can trip a bit from looking at this – use it wisely.
Source Michal Chovanec
Nice little grid. Would work great as a base on top of some other patterns.
Source Arno Gregorian
A free seamless background texture of "timber wall" (colored in dark brown).
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
ZeroCC tileable mossy (lichen) stone texture, edited from pixabay. CC0
Source Sojan Janso
A lovely light gray pattern with stripes and a dash of noise.
Source V. Hartikainen
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin