Adapted from an image that was uploaded to Pixabay by Anerma.
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
A seamless pattern formed from background pattern 102
Source Firkin
Prismatic Groovy Concentric Background No Black
Source GDJ
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay
Formed by distorting the inside front cover of 'Diversæ insectarum volatilium : icones ad vivum accuratissmè depictæ per celeberrimum pictorem', Jacob Hoefnagel, 1630.
Source Firkin
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Number 4 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
An alternative colour scheme to the original seamless pattern.
Source Firkin
From a drawing in 'Uit de geschiedenis der Heilige Stede te Amsterdam', Yohannes Sterck, 1898.
Source Firkin
This is lovely, just the right amount of subtle noise, lines and textures.
Source Richard Tabor
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
The image depicts the Japanese Edo pattern called "seigaiha" or "青海波" meaning "blue -sea- wave".I hope it's suitable for the summer season.
Source Yamachem
Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Prismatic Geometric Pattern Background
Source GDJ
This tiled background comes in red and consists of tiles that look like gemstones. It is more for blogs or social profiles, I think.
Source V. Hartikainen
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Zero CC tileable Laminate wood texture, photographed and made by me. CC0
Source Sojan Janso
Prismatic Rounded Squares Grid 3 No Background
Source GDJ
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
This background has abstract texture with some similarities to wood.
Source V. Hartikainen