Thanks for noticing! How annoying. That'll be down to the engine's default behaviour for 'examine' looking for an object. I think that's why I created the 'look' command (that and accessibility reasons). Must be an engine thing because it looks like the message appears after you've examined the sycamore tree once. If I ever revisit the code I'll be sure to fix this, alongside things like 'listen/hear' and 'smell' text.
Good work on finding so many mushrooms! The ending changes under many different situations, not just the completion of the game. If you find no mushrooms, for example, or if you add different mushrooms to the stew, or if you don't find certain objects.
If I got your juices running for text games, also check out "Hunter, in darkness", "A dark room" and "Hoist Sail for the Heliopause and home".