New bird in our backyard.

We have a new bird once again this Summer. It is almost as big as a Robin. Has speckled brown and black feathers. At the base of the back where the tail starts is a white slash of color seen only in flight. Has a long dark kind of curved and pointed beak. Have never seen this in Nebraska before. What is this neat bird? We know it's not a Thrasher we had a new pair of those nesting this past Spring. However it is about the same size. Please help me identify this bird.