Reminds me of Shelob from the "Lord of the Rings".
But less of a malicious movie-screen monster and more of an over-protective mother.
This is (probably) a female wolf spider from the genus Geolycosa
("earth wolf") in her den (possibly guarding an egg sack).
The burrow's opening was probably about the size of a silver dollar... perhaps a quarter... memory's fuzzy.
This is another photo from my family's trip down to Georgia last summer. We stopped of at a park in North Carolina called "Green Swamp National Park". It's one of the few places you can actually go to and see wild Venus Flytraps (though we did not find any while we were there.) We did manage to find plenty of other fascinating finds, though.
I must admit, spiders rarely intimidate me, but for some reason these guys are one of the few that do... I like wolf spiders, but this large one was more intimidating, I think impart because it was in a burrow, and only the business end of the spider was exposed.
More striking photos of female Geolycosids
with their eggs: [link] [link]
Still if I had to choose an invertebrate for a mom, I think I'd feel a lot safer with her as mine.