The name of the trashline orb weaver spider (Cyclosa turbinata) is derived from the thick vertical line of silk and/or debris in its web. Called the stabilimentum, the line may help stabilize the web, may attract insects, or may deter birds from flying through the web by making it visible.
The line of silk also holds debris, which the spider deliberately goes out and collects, creating an area of camouflage in which it is possible for the spider to hide. Can you find the spider in the above photograph? (It’s just below the first vertical gap in the stabilimentum.)
The above two trashline orb weavers are also probably C. turbinata, just based on geography, but I would have had to disturb them and flip them over in order to identify them properly.