One of them have to be The Watcher in the Water. Not sure about the second one though. I see footprints leading from the water which could be a reference to Gollum. I see a face in the tree which could be a reference to Ents. And there might be a body at the roots of the tree? If so, that would be a reference to Boromir of course.. But its very vague, I think I'm seeing things that aren't there. It's probably something else.

Ok, I get it I think. It's not a body perse, it's body being covered by roots and shrubbery. Which means its a reference to Old Man Willow.

It is Old Man Willow. When he trapped Merry in his trunk with only his feet sticking out.

Yeah, that kinda threw me for a loop because since its line art the feet could also kinda be more roots from Old Man Willow :). But I'm glad I caught it in the end.