I was trying to do dandelion once. We had enough dandelions, but you have to only take the petals & it got tiresome doing the collecting. Your FIL might’ve gotten part of the green stuff in there. The weirdest one we’ve done is banana, using dried banana chips & raisins. In the primary fermenter it smelled like sour milk. I almost tossed it, but decided to keep going. It gradually lost that smell & turned out to be an okay mild white wine. Didn’t taste much like bananas, though.
One year, my SIL gave me a wine-making kit for Christmas. I followed the instructions precisely and scientifically, bottled it up, and drank it.
That stuff was like a dry Port - or harder. Gave me the only real ‘hangover’ that I’ve ever had.
I gave up on making it, and buy my wine - though I’d always rather have a Guinness :-)