It appears that the center of your floor is lower than the rest of the floor.
I had this problem with a house that I used to own. The house was built on land that was filled in, (it used to be a wetland).
After spending a week in my basement (supposed to be dry, no sump pump), I broke through the floor and the floor was only about an 1 1/2" thick at that spot, the water rushed in. I dug down and relocated the sump to that location.
You may have a natural spring under your floor that the water from your neighborhood drains to?
This is a problem that I would go to the Building Inspectors office and find out what the area was like before your house was built and I would also look to see if there are any flood maps of your area.