As of right now, there is no item value list or website that is officially made or endorsed by Adopt Me!
However, if you're lost and unsure what your items are worth, we recommend heading to our official Discord server and checking out our dedicated Trade Discussions channel and our "Win/Fair/Lose" channel to find out more about your items and trades.
To join our Discord server you must be over the age of 13 as per Discord's Terms of Service.