Oh... so that's why Tewi is cracking popcorn puffed rice over there. 😀🍿

Huh? Do they even have corn Gensōkyō? 🤔 I suppose we can imagine Yūka keeping a field. You know. Cornflowers got the name from being weed in corn fields. So it makes sense for her to grow corn along with her pretty cornflowers.

The part that would make this not sensible – which then makes it a very Tōhō detail – is the fact that "corn" in cornflower meant grain (like wheat).