Definitely wait to order parts until you get it out and opened up. Those look like pieces of the intermediate band (front postion in trans). Breaking only that band should have still allowed reverse gear and first gear to operate normally, if there was no major fluid leak. That means the damage may be worse than just a broken band. Hope it's not too bad though.
This ^^^ can't imagine that much crap and fluid that brown without expecting that all that grit and metal filings has been through the valve body and even through the splines , sorry bud but that could be nasty .
