It's possible they're nothing to do with the Midas, and a previous owner has thrown them in the car in annoyance at forgetting what he made them for, and then putting them out of his mind...

I didn't have a rear seat in my Bronze, and I don't recognise them, so could well be seat parts. Can you give some idea of scale? How thick is the metal, how wide is it, what size are the bolts?