Signs from ASL that have two unrelated meanings and thus are lexically ambiguous: 1) “nation / of course”, 2) “booth / person” 3) “everything / involve” . You can see pictures of them on page 130 of
Emmorey, Karen. (2002). Language, cognition and the brain: insights from sign language research. Mahwah, NJ: Lawrence Erlbaum.
Lexical ambiguity is rife in signing but hard to explain in English (a lot of it is bilingual puns). A good source is
Sutton-Spence, Rachael (2005) Analysing Sign Language Poetry. NY:Palgrave-MacMillan. Chapter 6 is entirely devoted to the subject of ambiguity in signed languages.
A somewhat accessible example is the genre of ABC stories, where the hand shapes are letters of the alphabet and at the same time signs that tell a story. You can see one in this video, with the English letters corresponding to the hand shapes shown on the screen, and you should be able to guess what the story is about.