My $9 pot of chili turned into $25 because I forgot to check the pantry

I was at the Aldi on 5th in Springfield last Saturday trying to make a cheap pot of chili for the week and figured $9 would cover everything. Got home, opened the cabinet, and found out I already had two cans of beans and half a bag of rice, so I basically bought doubles of stuff I didn't need. I went back the next day with a list written on the back of an envelope and got $6 back on returns, then used that to grab a bag of frozen corn and some cheap ground turkey instead. Now I keep a running list taped to the inside of the pantry door so I don't do that again. How do you all keep track of what's already in the house before you shop?