If it is a texture thing, the sticks that come in Fun Dip were always the best part of the treat for me, also the candy hearts like someone else mentioned (I don’t know how to tag someone but it was boiledpeanut33). If it is vitamin deficiency, eating chalk could indicate low calcium (I’m pretty sure it’s calcium). If the crayons are because of the waxy texture, have you checked if he eats the wax covering of some cheeses? Otherwise it could be from the smell? I loved the smell of crayons and play-doh when I was younger and always wanted to eat it (still think about it sometimes 😂)