I'm using MAMP on a MAC. And in the php info page on MAMP, it says that mcrypt is enabled. However, when I run "php -m" on the terminal, I can't find mcrypt between the php modules.
I don't think MAMP relies on the php package installed in Terminal (or in OS X for that matter). MAMP uses it's own php version located at
The modules are in the folder I noted above in a subfolder called /modules. You would have to manually get mcrypt in the modules folder for MAMP to work with mcrypt.