Not so subtle. These tileable wood patterns are very useful.
Source Elemis
Based on an image that was uploaded to Pixabay by devanath
Source Firkin
The image depicts a seamless pattern of a tortoise in tortoiseshell (hexagon).
Source Yamachem
The Grid. A digital frontier. I tried to picture clusters of information as they traveled through the computer.
Source Haris Šumić
A very dark spotted twinkle pattern for your twinkle needs.
Source Badhon Ebrahim
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
Free tiled background with colorful stripes and white splatter.
Source V. Hartikainen
One can never have too few rice paper patterns, so here is one more.
Source Atle Mo
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Number five from the same submitter, makes my job easy.
Source Dima Shiper
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
Prismatic Abstract Geometric Background 4
Source GDJ
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
An abstract pale yellow paper-like background with stains colored in yellow and green.
Source V. Hartikainen
The image depicts a seamless pattern made using a bird's face.
Source Yamachem
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
A brown seamless wood texture in a form of stripe pattern. The result has turned out pretty well, in my opinion.
Source V. Hartikainen
The file was named striped lens, but hey – Translucent Fibres works too.
Source Angelica
One more sharp little tile for you. Subtle circles this time.
Source Blunia
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
A hint of orange color, and some crossed and embossed lines.
Source Adam Anlauf
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić