Reading a post above from Doug64, I thought of this particular campsite I was in. I was the only tent camper, am in the middle of five tent sites at this RV park and campground.
Ground was very flat. I knew from the forecast that significant rain was coming, decided to stay there for a couple nights to sit out the rain. Walked around the campsite for a while to find the highest piece of ground, which was probably slightly higher from the tree roots.
I was fortunate in my tent site selection, my tent stayed dry. And much of the area had puddles that were shallower than the height of the grass, thus when walking around in the area that looked grassy, you were also walking in shallow puddles.
I mentioned above that I have some good lightweight one and two person tents, thus I have no interest in sleeping under a tarp this time of year. I think tarps are great in snow camping, but not so much for rain camping.