You're welcome!

You have to go to Veta and plant a seed in the gardens. As far as I can tell, it doesn't matter which seed you plant, I just bought a bunnion seed from seedlings and used that. It takes about three days to do and you have to water it every day but once it grows and you harvest it you'll get a little notification that says "You solved the riddle! The Autumn Sphinx Trinket in your inventory has been replaced with a Autumn Sphinx Cuirass".

Oh you also have to have the trinket in your inventory when you do this, so I just locked mine so nothing happened to it during those three days. :)

Hey, do you still need help figuring out the riddle for the Autumn Sphinx Trinket?

No problem!

Aw, thank you very much! I'm using these items: