I was in Kroger and had a jicama among my purchases. The clerk, a young man, said, "You're gonna have to tell me what this is." as it had no identifying sticker. I said, "It's a jicama." He began looking at a chart. I noticed he was looking in the "H" column. I said, "Oh, it's spelled J-I-C-A-M-A". He said he'd never heard of it and asked how it was used. I told him I was going to use it on a vegetable tray I planned to make.
When he found it on the chart, he mentioned that they were expensive. I said, "Gosh, I could have told you it was a turnip; they are a lot cheaper." He said, "Aww, you wouldn't do that, would you?"
Each year, Mother would peruse the Burpee seed catalog and she would choose an unusual vegetable to try. Over the years we had an assortment of squashes (turban, patty pan, acorn, zucchini, and spaghetti squash), rutabaga, salsify, kohlrabi, and leeks. She had no luck growing cauliflower and broccoli.
One year she chose jicama but they were not a favorite and she never ordered them again.
Of course, at that time we didn't know the proper pronunciation and said "Juh-cam-uh" as any Fayette County HICK would.