Oatmeal vs. Rice Cereal?! Thoughts!

Thinking of giving my baby some oatmeal or rice cereal. She's been spitting up more and I thought it was teething but think she could be hungry and her stomach isn't settling with all the milk. I think a little substance will help keep the milk down and maybe help with her spitting up so much. Any recommendations? Which brand? I am using all organic products thus far.