Zero CC tileable grass texture, photographed and made by me. CC0
Source Sojan Janso
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Abstract Geometric Background 4 No Black
Source GDJ
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
Semi-light fabric pattern made out of random pixels in shades of gray.
Source Atle Mo
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Same classic 45-degree pattern, dark version.
Source Luke McDonald
Prismatic Hypnotic Pattern 2 No Background
Source GDJ
Prismatic Abstract Geometric Background 5 No Black
Source GDJ