The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A bit of scratched up grayness. Always good.
Source Dmitry
A seamless pattern formed from a sports car on clker.com. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Chevrons Pattern 5 With Background
Source GDJ
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Hey, you never know when you’ll need a bird pattern, right?
Source Pete Fecteau
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
The image depicts meshed silhouettes of various things.The original image is an OCAL clipart called "Enter FOSSASIA 2016 #IoT T-shirt Design Contest" uploaded by "openclipart".Thanks.
Source Yamachem
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
A version without colours blended together to give a different look.
Source Firkin
A seamless light gray paper texture with horizontal double lines.
Source V. Hartikainen
Prismatic Curved Diamond Pattern 7 No Background
Source GDJ
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
Alternative colour scheme for the original floral pattern.
Source Firkin
Formed from decorative divider 184 in paint.net. Vectorised with Vector Magic.
Source Firkin