These are called pastelitos in Spanish. The sweet ones are made of thin pasta and have different types of filings such as guyava, cheese, apple, mango..etc. The salty ones are made of potato and cassava (yuca).
You can find more about cassava (yuca) here:
The Cuban Bakery.
The Bakery from the front.
And now I am laying in the bed with a full stomach. I can't even move.... :)