Passion flower is probably my favorite because its astonishing up close and impossible to find except in certain locales. Plus its native to Eastern US forests.
but a veery close second is Trillium because its this supposedly rare plant (regionally dependent) and the first time i found it I was so far off trail at this stream where i was finding all of these supposedly rare species in groupings by the hundreds. That was a huge day for me. Not to mention its beautiful, and it brings back so much nostalgia whenever i see it. Oh and its uncommon to see it in bloom, so that makes it even more special. 90% of the time i find it after the flower has dried up.
Both these pictures were taken by me btw