So... my USB's were sent "First-Class Package Service" for several days when I entered my tracking number... nothing showed up... Now under status I see "Electronic Shipping info Received" with a date of May 31, 2013. ...what does this mean? Does this mean they JUST started to send it on my way? I assumed at first this posting method just did not have tracking.
(glances over at his lonely Raspberry Pi)
It means you've discovered that USPS tracking is useless

This is true all of the time and not just with these shipments. Mostly it's only useful after the fact to confirm delivery has happened. In my experience, it is almost never useful in understanding what is happening mid-delivery.
USPS told me it would be delivered on Friday, and I received it on Thursday. So... I agree, USPS tracking is virtually useless.