It took me a little searching to find where MAMP Pro (I couldn’t say whether MAMP is the same) puts its MySQL data files, so I thought I’d blog it:
/Library/Application Support/living-e/MAMP PRO/db/mysql
I had been looking in my User directory’s version of the same path (which is where MAMP Pro stores config files), but it makes perfect sense in this context that databases are shared while configuration isn’t.