What is the meaning of the tongue twister she tries to trace two trays under those trees because there's no trace of two trays trace under those trees?

Okay. Let's say there is a girl tracing into the dirt right under a tree and she is tracing trays. I think the tongue twister is saying that she is doing it because there is no trace or hint in the dirt that two trays were there. I'm just guessing, though.