The kind of mushrooms you buy in the store would be ok for your tortoise, but I don't like to feed them to sulcatas. I doubt a sulcata would find a mushroom in the wild.
Celery has no food value and alfalfa is ok on a limited basis...not every day.
ok thank you guys very helpful I just want to get my guy back on track btw I have a post in the introduction area if you want background info on goliath