Stressed about money

I am so stressed about money, especially the price (cost) of groceries. I went over my $100 budget again last night. The tears were almost flowing in Wal Mart. I don't know what to do. Does anybody have any ideas? I feed four people, including two teenagers. We eat very modestly. Nothing fancy. I make my own laundry stuff, noodles, and biscuits. Help. Any ideas would be appreciated! Thanks. Kimberly