CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
You just can’t get enough of the fabric patterns, so here is one more for your collection.
Source Krisp Designs
The image a seamless pattern derived from a weed which I can't identify.The original weed image is from here:https://jp.pinterest.com/pin/500744052301423641/
Source Yamachem
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
Prismatic Curved Diamond Pattern 7 No Background
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Basket Fibers, Basket Texture, Braid Background style CC0 texture.
Source 1A-Photoshop
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
I skipped number 3, because it wasn’t all that great. Sorry.
Source Dima Shiper
Similar to original, but without gaps in between the arrows. This seamless pattern was created from a rectangular tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
Kaleidoscope Prismatic Abstract No Background
Source GDJ
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
Gold Triangular Seamless Pattern No Background
Source GDJ
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
A series of 5 patterns. That’s what the P stands for, if you didn’t guess it.
Source Dima Shiper
A simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib
Lovely pattern with splattered vintage speckles.
Source David Pomfret
From a drawing in 'Bond Slaves. The story of a struggle.', Isabella Varley, 1893.
Source Firkin