Big timber rattlers; aka canebrake or chevron (shape of markings) or Seminole rattler. While the eastern diamondback is known as a gentleman viper because you truly have to work at him to get him to strike, these often fail to rattle and will strike quickly. In case you care, they are easy to skin....use some push pins ($1 for 100 at any dollar store) to pin them flesh side up on a long board. Cover EVERY part with a 1/4" layer of borax...Mule Team is a common brand available in any laundry detergent area of a market. In three to five days of leaving in the sun, un-pin, shake the borax off (it's not toxic or corrosive), wipe off and spray scale side with a good quality high SPF sunscreen and it'll last for years.