Smugleaf was a series of levels that was made in the very beginning of Everybody Edits, before even dragging to add bricks was added.
Smugleaf paved the way for platformers today, as it was one of, if not the first level to feature a lot of the most used puzzles today.
There have been a Smugleaf 1 and 2, and possibly a 3. A Smugleaf's Revenge level was made however the creator fell victim to the the lobby boot glitch and lost the level; there hasn't been another Smugleaf since.
Unrelated to Everybody Edits, Smugleaf is the fan name for the grass starter in Pokemon Black and White.