I know jedi josh's trainer has I believe all plants in the spawn object category. I don't know if you can pick them after you spawn them though I guess I haven't ever tried.
For me pelts seem to stay at whatever star level the animal was to begin with. This is regardless of the amount of times i shoot it and how many times i shoot it. This however isn't always the case as sometimes i can get an animal that starts as a 3 star and goes to poor like it normally would so it's kind of hit and miss
The only animals that seem to always be 3 star are animals you pick up their carcass instead of skinning (squirrels, birds).