I noticed webs with small leaves and twigs in the center, that changed from day to day.

It was a combination orb web and "random" web. One was in a tree, another on a tomato plant.
At the center, on close inspection, was a spider, hidden from above, by "junk" gathered around it.
Small twigs, bits of fallen leaves and bug carcasses. Never seen anything like it before.
I suppose the purpose is to trick birds and other predators into ignoring it.
The spider was visible if viewed from below.
-