I need help with our new house. Our back half of our yard floods bad when it rains. I think the houses around us lower into our yard. Does anyone have any sugestions?

your house must lie in a valley. other than trucking in topsoil and grading it away from the house, I don't think there's much to do.

First I would ask the local municipality to check the culverts and drains in that area. Then I would buy several truckloads of dirt and make my yard the highest. It is just a law of nature that water runs to the lowest point it can find, just make sure your yard isn't that place.