I found out about these little fellows years ago. I was dating a girl in Houma, and when I went down to visit her the first time there in Houma, she ran into a gas station and grabbed a pack. She ate them like you would eat peanuts. I actually developed a taste for them and would pick up a pack from time to time. They are primarily used to make shrimp stocks and add to a gumbo. As for a snack, you REALLY have to like the flavor of shrimp. They are tiny and a bit chewy but after the first few, they're like... jerky, in a way.
These are available all over Louisiana in grocery stores, convenience stores, etc. You can also order them from places like Simply Cajun or from Pure Cajun Products. They also make dried shrimp powder that you can toss right into a pot of boiling water and SHAZAAM... great shrimp stock. This and the dried shrimp pictured are from Rouse's Supermarket. Whether you use them for stock or gumbo, or decide to eat them as a snack, this is TRUE Louisiana.