Medium gray pattern with small strokes to give a weave effect.
Source Catherine
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
The image depicts a seamless pattern of pine tree leaves.
Source Yamachem
Green Background Pattern
Source V. Hartikainen
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
From a drawing in 'Heroes of North African Discovery', Nancy Meugens, 1894.
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Colorful Floral Background 3 No Black
Source GDJ