Can an Arduino emulate a USB mass storage device? Question:

Can I connect an Arduino's USB port to the USB port of another embedded device that is expecting a USB thumb/flash device? 

Or, can I connect a USB module to this embedded device, with the other end connected to GPIO's of the Arduino?

This embedded USB thumb device requires a thumb drive to transfer a file. I need to emulate the connection, disconnection, and thumb drive with the folder and file with a Arduino.

Is it possible to emulate an USB thumb drive between an Arduino and an embedded device's USB port?

Research:

I saw a couple other questions that talk about USB being a master/slave configuration and that certain IC are required. Additionally, that there were some cables that can be used for two-way data transfer (mostly for PC to PC data transfers). If that is the case, could one of those cables be used for this configuration? Which cable would work?

Possible Solution:

The embedded device I need to emulate a thumb drive on will automatically search for the file in a specific folder of the thumb drive. Would I be able to partition a section of an SD card with the SD card module to appear as a thumb drive, and then connect that partition to the embedded device via USB-A to USB-A cable?

Diagram:

Arduino USB Port -> USB Cable -> Embedded Device USB Port
Arduino GPIO -> USB Module -> USB Cable -> Embedded Device USB Port

Requirements:

Connection via USB cable between Arduino and an embedded device's USB port.
Ability to emulate the connection and disconnection of a USB thumb drive on the embedded device.
The description of this device from Sparkfun appears to match the OP's requirement for integrating an Arduino with other USB devices by enabling the Arduino to acts as a USB host. https://www.sparkfun.com/products/9947