Not so subtle. These tileable wood patterns are very useful.
Source Elemis
Zero CC tileable ground (#2) cracked, crackled texture, made by me. CC0
Source Sojan Janso
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
Inspired by a design found in 'Konstantinápolyi emlékeim', Miklos Chriszto, 1893.
Source Firkin
Seamless Prismatic Geometric Pattern With Background
Source GDJ
Number 3 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Prismatic Snowflakes Pattern 2 No Background
Source GDJ
Here is a new seamless wood texture for using as blog or website backgrounds.
Source V. Hartikainen
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective