From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Kaleidoscope Prismatic Abstract No Background
Source GDJ
Black brick wall pattern. Brick your site up!
Source Alex Parker
Zero CC tileable seed texture, edited by me to be seamless from a Pixabay image. CC0
Source Sojan Janso
Simple combination of stripy squares with their negatively coloured counterparts
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Prismatic Floral Background No Black
Source GDJ
Prismatic Groovy Concentric Background 5
Source GDJ
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
An aged paper background tile with smeared and pressed text.
Source V. Hartikainen
Dark, crisp and subtle. Tiny black lines on top of some noise.
Source Wilmotte Bastien
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
This is a seamless pattern of regular hexagon which has a honeycomb structure.
Source Yamachem
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
Based on an image that was uploaded to Pixabay by devanath
Source Firkin
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin