FYI when I wasn't able to place my "input", I just hovered my mouse all over the place and some strange placements were allowed
That's how I got those sticks'n mushrooms floating :0
Also you can just infinitely place "up inputs" on the top of the middle tree
Aaand if there is a "2 inputs wide twig" and it has a mushroom on each "twig space", you can remove the space under the first twig and destroy both mushrooms
Love discovering bugs :3