@lilmeli15 no you can't but Walmart does have a parents choice brand of formula that is the same as enfamil(if thats what you use) the small one is around $8 and the biggest one is $19. I do that when my son runs out of his wic formula.
Unfortunately, no. Try a food pantry, see if Dr has samples or buy a can. I also see he's almost 1 year old, he'd probably be fine to just give some regular milk to.