I understand what joebryant said, since it may very well seem like an exaggeration. Not many teachers would want to grade that much homework, so it could be hard to believe. Except for one little thing. I know for a FACT that when I was in school that some of our assignments would not get graded based on how many we got right or wrong, but instead whether we turned in a completed assignment. The teacher DID NOT CARE whether the answers were right or wrong, just so long as we sat there and did the darn work. Homework supposedly builds character. Right. The other thing that some teachers did would be to alternate grading. Say a teacher teaches 6 classes per day, and assigns homework for each. Monday's homework would only get graded for classes 1-3, while the other three classes just get credit for turning the assignment in. Then, on Tuesday, classes 3-6 would get graded, while the other three just got completion credit. Or, only random assignments from each class would get checked. 
There are two other option: either you are exaggerating (not likely, it hasn't been that long since I was in school and I know how psycho teachers can be....) or the teacher really is nuts and grades all that work instead of having a social life, eating, sleeping...etc. Which is also possible. I had a teacher in high school that hated kids, period, and for some reason her life revolved around making us miserable. The worst assignments, the hardest problems, the longest studying....it was terrible. Her excuse was that it prepped us for college, but man, you can tell when someone hates students. And this teacher despised us.
He did make a good point: how can she keep getting away with this for so many years in a small town? probably because it IS a small town! You said yourself that she buys eggs from you. It's easier to get away with stuff if you know everyone that makes decisions! That's what the teacher I had did. She hung out with the principal on the weekends, spent time with the school board members. She was making a pretty decent wage, from what I heard, too....just greasing the wheels, or 'job security'.
As far as being offended by what joebryant said, don't let it get to you. There have been a few people here before that blow their stories out of proportion just to get sympathy. I honestly don't think you're one of them, but that's just because it's only been 5 years since I was in school. Some teachers are good, some school districts even, but there's always a lemon somewhere in someone's hometown. Just so happens to be yours. I personally was very interested in this thread and finding out what happened, cause ever since dealing with the nutjob teacher who hated all of us it'd be nice to see what happens in your case. 
Oh, and this is how we handled it: almost everyone who took her class passed with -D's (I was an overachiever and bumped up to a B), and we did so PURPOSEFULLY. Which says a lot for how you're handling it, I would just tell the teacher to go where the sun don't shine and give my kid permission to fail the class. Please keep updating us!