Ok. States are not allowed to do some of the things the feds were put in charge of. Not sure why you mentioned it though.
I dont think there is a State with enough gold to mint their own coin.
The economy would literally bind up overnight if we switched to a gold backed currency. Lots of t bills would be sold to exchange with a hard currency. Lending would pretty much stop.
In the end, the amount of money in circulation would drop like a rock because the line at the gold window would be miles long. The bonfire of dollars needing to be destroyed would light up the skies.