The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
The image depicts a seamless pattern made using a bird's face.
Source Yamachem
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
Prismatic Geometric Pattern Background No Black
Source GDJ
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
The name tells you it has curves. Oh yes, it does!
Source Peter Chon
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Remixed from a drawing in 'Canadian forest industries July-December', 1915
Source Firkin
It’s a hole, in a pattern. On your website. Dig it!
Source Josh Green
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A free background pattern with abstract green tiles.
Source V. Hartikainen
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki
Seamless pattern made from a tile that can be obtained in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Prismatic Snowflakes Pattern 2 No Background
Source GDJ
A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
Inspired by a drawing seen in 'City of Liverpool', James Picton, 1883.
Source Firkin
Original minus the background
Source Firkin