Uneven lawn?

Uneven lawn?

We recently moved into our house and are just starting to fix up the yard-gone-feral (the house was empty for six months, which is also about as long as our summer season is here in Florida). As I'm getting out and about, it's very obvious that our yard is uneven. There are a couple of places that are 3'-across circular areas that dip down by an inch or two. They are somewhat hazardous during the day and I expect they'll be even worse at night. Is there a quick and easy way to fix them? We're having our housewarming weekend after next so I'd have this weekend to work on it (stupid non-daylight savings time taking all the weekday sunlight away from me!). I'd also be interested in solutions that take longer because, hey, it has to be fixed eventually. Oh, this is also in the back yard so it's okay if it's a little unaesthetic for a while.
Lemon Chicken Scaloppine

Lemon Chicken Scaloppine

Snapdragons

Snapdragons

Things I think are weeds in the Garden of Guessing

Things I think are weeds in the Garden of Guessing

Flowering bush ID

Flowering bush ID

Simple biscuit recipe

Simple biscuit recipe

Three unknown trees with berries

Three unknown trees with berries