This morning's prompt is 'mustard', and I found the plant.

"What's this yellow stuff, with the little flowers," Tom asked.

Brenda looked at it and swore, but happily. "Eff me! That's mustard."

Tom had a confused look on his face and then the penny dropped. "This is the plant that they make mustard out of?"

"This is the plant we used to make a lot of stuff out of..."