HAHAHAHA I had to look for that one.... Here is what I have found:

http://www.northern.edu/natsource/REPTILES/Prairi1.htm ;
---People kill rattlesnakes mostly out of fear, although some folks kill snakes to eat. Rattlesnake skin is used to decorate many
items including belts and hat bands. People are allowed to collect prairie rattlesnakes for personal uses, but they must have a
fishing license to do so. To harvest large numbers of snakes for commercial purposes, a person must have a commercial
collecting permit.

I looked all over the SD Game Fish & Parks site, and I could not find anything about it.