how many turkeys will i need to prepare if i'm cooking for a 100 people and I have mac/cheese, mash potatoes, gravy, greens, rolls, pie, and ham?

LOU, I haven't tried really testing this out yet, but the free online portion calculator Guestimator looks interesting and may be of help to you:
https://savethefood.com/guestimator
I tried quickly putting in the items you listed and the results look reasonable. Keep in mind the edible yield of a whole turkey is about 53%, which means Emma's suggestion of 1 lb (raw uncooked whole turkey) is about right for a 1/2 lb serving. That's probably a little high since you're also featuring ham. My quick calculations from the Guestimator point to 3 ~15 lb turkeys, but that feels low. I once cooked a Thanksgiving meal for about 45 people at a local food bank and featured 2 large (18-20lb raw) turkeys but no ham. The portions were about right. Good luck!

Hi Lou! Wow! The general rule of thumb I've heard is: 1 pound turkey per person. Which would amount to roughly seven 15-pound turkeys. That said, it sounds like you have a lot of hearty sides—plus the ham!—so maybe six or even five turkeys would work, too.