GF,Chip-Munks eat a lot of different things,even baby-mice,birdseggs,worms(read on Google) etc..but here they eat sun-flowerseeds,peanuts,corn and suet.
We don't like Oreo-Cookies so we will not buy any,but I can see Melindas point,if you work with wild-life and need to get them to take meds.
I think if you want them to come up to you,a peanut would probably be enough.
We were just watching one of the Chippies digging like crazy,soil flying all around him