OK, I figured that the only way to remedy my struggle with drawing feet is to make a concerted study of them. So I took a bunch of photos of my feet and my partner's feet from which I will make some study drawings. I decided I'd put them up here for anyone else who could possibly make use of them, since they took me so long to collate. My apologies if there are any double-ups, and that some of them are fuzzy.
If you do use them, acknowledgement is appreciated.