If you didn't want it in the first place...please find a way to release it back into the wild. It will save you the trouble of getting it to eat and possibly save the snakes life. Good luck.
The widest part of its body is about this big, O. Now that i have it, i kinda like it. Thats why i told him not to bring it to me, i cant get rid of anyhting. I had a small garter snake for eight years and it was my favorite pet.
try catching some small insects were their isn't any insecticides sprayed and get a small baggy of them and place one at a time with the snake. I would try small ants such as sugar ants, is what ive seen small wild red racers around here eat.
you should beable to find baby pinkies at a local pet store, a snake can take down food 2/3rds bigger then the thickest part of its body, if those baby pinkies are just to big then i would suggest feeding crickets. the snake will get more protein out of crickets then feeder fish. but primarily you want your snake eating mice over crickets. another thing you can do is while the pinky mouse is frozen you can cut it in half , lengtweise and feed it like that, the smell of the blood should drive the snake crazy. good luck