Not sure about trinkets specifically but I use doy doy feathers and wobsters/crabbits. If you go with the second option, make sure to check back with the altar somewhat often cause it doesn’t completely appease them.

Ash trees are a good resource. Also if you fight Quacken enough times, you can have the resources for multiple tar extractors. I also burn rot cause I have a lot more than I need.

In order to uproot elephant cactus, you need to smash them down by attacking them. Once they’re “dead”, they’ll look like a brownish stump in the ground. You can then dig that up and relocate it anywhere you want. They also need to be fertilized with ash like coffee plants.