A repository for max flow and mincut datasets
To test correctness: the set of edges belonging to a min-cut is not unique in general, so a dataset like you ask would not really be helpful, apart from checking that the value of the cut is the right one. However, it is easy to check correctness yourself by using the output of your algorithm if you compute both the max-flow and the min-cut; just check that the first is a valid flow, the second is a valid cut, and that their value is the same. By the max-flow/min-cut theorem, they must then both be optimal. 

To test speed: it's pretty old (1990-91), but you may want to have a look at the archive of the DIMACS implementation challenge on the Maximum Flow problem. It includes many generators and several other codes. For a more modern dataset (1998-2013), here is a collection of Maximum Flow problems arising in computer vision. Also, Andrew V. Goldberg has a page on network optimization software with several useful links (although the Min Cut one seems to be dead).