Looks like it was Drout's Quick and Easy Old English, which has the advantage of being pretty cheap.
The Kindle version is OK, but a dead-tree would be nicer (I found myself using bookmarks pretty heavily to refer back to things.)
If you'd like to see a page or two, let me know what you want and I'd be happy to provide.
bonus: All professors' websites are garbage.
>Old English Wikipedia
of course that's a thing.