This was formed by distorting an image of a background on Pixabay.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Not the most creative name, but it’s a good all-purpose light background.
Source Dmitry
Prismatic Groovy Concentric Background 4
Source GDJ
A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
Small dots with minor circles spread across to form a nice mosaic.
Source John Burks
Prismatic Basic Pattern 2 No Background
Source GDJ
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Simple combination of stripy squares with their negatively coloured counterparts
Source Firkin
This was submitted in a beige color, hence the name. Now it’s a gray paper pattern.
Source Konstantin Ivanov
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin