This could be a hippy vintage wallpaper.
Source Tileable Patterns
A heavy hitter at 400x400px, but lovely still.
Source Breezi
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Remixed from a raster on Pixabay, that was uploaded by ArtsyBee.
Source Firkin
A classic dark tile for a bit of vintage darkness.
Source Listvetra
We have some linen patterns here, but none that are stressed. Until now.
Source Jordan Pittman
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A frame using leaves from an image that was uploaded to Pixabay by mayapujiati
Source Firkin
Zero CC tileable seed texture, edited by me to be seamless from a Pixabay image. CC0
Source Sojan Janso
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Remixed from an image that was uploaded to Pixabay by CatherineClennan
Source Firkin
Geometric lines are always hot, and this pattern is no exception.
Source Listvetra
Prismatic Chevrons Pattern 5 With Background
Source GDJ
Prismatic Basic Pattern 2 No Background
Source GDJ
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8