Because of the variations in the series, I would suspect they came from a collection somewhere. From time to time a silver certificate will show itself in circulation but not often. The have long been removed from circulation, but there are still large quantities in public hands (stowed away somewhere).

1957 was the last year they were produced, but were in circulation well into the 60's. Without seeing them a value would range from Face Value to $5 in uncirculated condition according to one of my reference books. I believe the book value is a bit low on the bottom end since I see them going for $1.50~$2.00 in any condition.

The STAR note denotes a bill was damaged in production and it was REPLACED with the Star Note to keep the numeric sequence. Star notes are generally worth slightly more.

I would keep them or sell them to a collector (or offer to exchange them with current notes from the student). Don't spend them, if they make it back to the FEDERAL RESERVE they will just be take out of circulation and destroyed.

Lastly, I would buy them (but I usually advise no to sell to the person who gives you the value, even me).