Hi Dawn,
You have many responses here and lots of good information to go by, but I just had to add this. You say your mom keeps your son while you work. Does the same thing happen with her or what does she feed your son? We love our moms dearly, but I found with my daughter that my mom did lots of things I didn't approve of when she was with her. Some of the eating habits there was one of the main things. It didn't matter what time of day or night it was, if my daughter wanted a jar of jelly, my mom would give it to her. It didn't matter where she wanted to eat, my mom let her, if it was in the middle of the bed. While at home, I found persistence to be the best thing for us. Also a multivitamin. My daughter went thru stages of only one food at a time. I always said I should have taken stock in ketchup and chicken I could have been rich to this day,,LOL. She would eat any kind of chicken you gave her as long as she had ketchup with it. I didn't fix special things for her for dinner, I would give her a little of everything we ate, she would then either eat it or she didn't, but she had to sit with us till we were all done eating. (actually that was my trick to get to eat myself instead of chasing her around at dinner time,LOL) For breakfast or lunch I usually let her tell me or show me what she wanted as long as it was something healthy and something I had in the house. If it was just a piece of cheese or a hot dog wiener for lunch,(not a jar of jelly,lol) that is what she got. Of course before she was big enough to tell me or show me, I just tried lots of things. She got stuck on one item though and then finally would move onto something else. As time went on, she eventually started eating really good for dinner on her own because it was sitting there in front of her every day. Be persistent with what ever you do or give him, also as to where he eats and what time, and eventually he will see that is what is the norm for him. Don't worry too much, if he is hungry, he will eat what you give him eventually. I made it, and many more moms have made it, you will too. My daughter is now 20 yrs old, eats probably more healthy than I do, and more variety than I do. So it will eventually work its way out if you just keep giving him healthy things and by all means the multivitamin! You also might want to discuss your plan with your mom and insist she do the same as you do. Good luck and don't worry too much!