Crawsack

The Sonoran Desert Toad. The only place I've ever found is east of Catfish Jackson's, south of Bolger Glade. If you ride your horse along the road right along the water, one will often come out of the woods. Otherwise you may have to ride through that woods but be prepared to be bucked off your horse and have very little time to react. The only way I've been able to track and study panthers/cougars is by shooting them with a poison arrow, they run away from you then while they're dying you can track and study them. Otherwise it's basically impossible because you'll never sneak up on them.

You can get 38 out of 43 in the main map. 1 you can find just outside Blackwater (Prairie Poppy). Desert Sage, Red Sage, Blackcurrant, and Wild Feverfew you can only find in New Austin. But you can use a covered wagon to get into New Austin as Arthur and pick those plants even with the sniper shooting at you, there are guides on Youtube on how to do so.

That's weird, cool that it works for you though.

How do you send them off in the mail? I've never had that come up as an option when I go to the train station.