The wreckage is all that remains of Cassidy Caravans, the company belonging to Cass that the Courier barters with her for, on behalf of Alice McLafferty. The caravan's remnants contain a dead brahmin, a wooden cart, one small crate with various loot, several small wooden boxes and crates, an ash pile, and many drained energy cells scattered on the ground. It is possible to encounter cazadores nearby, as well as Legion assassins.
The flies circling the brahmin corpses are actually bloatflies shrunken down to size.
The Cassidy Caravans wreckage appears only in Fallout: New Vegas.