Is It Too Much to Feed a 15-Month Old Boy About 1/2 to 3/4 Cup of Rice?

All of those items you mentioned can move through the system pretty quickly. It does not look like there is much protein.
Are you a vegetarian? If not, maybe try some chicken? If so, maybe some beans or cheese? My kids love all of the above. I try to make sure they have some protein at each meal, though my son will sometimes only eat noodles!!

Another thing I have noticed with my kids is that their appetites come and go. They may eat a lot over one or two days and then really lightly over the next day or two. Then repeat.

Other than that, unlike adults, most babies know when they are full. :)

Hi E.,
I have always heard that you should let them eat as much as they want to when they are young that way the child will learn when they are full, it helps the child not have issues with food when they are older. They will let you know when by turning away or refusing the food when they are full.
My children have all loved avocados, cheese cubes, peas, green beans, steamed carrots, steamed broccoli/cauliflower, fish, etc. By 15 months they pretty much eat whatever we eat, and as much (or little, my 2 yr old eats like a bird-lol!) as they want.
I know it can be worrisome as well all want what is best for our children, but sometimes letting them decide is what is best :D
Good Luck mama!

Hi E.,
Melissa & Skye both have great advice, but don't forget the vegetables!!!

In addition to feeding, how about hydration? I noticed my son was constantly hungry, until I had him hydrating...very important. A child must have constant hydration for brain development.In addition to milk add water to his diet.

I don't know if it's too much. I assume he's pooping fine. I do remember my son having a HUGE appetite around that age. Then, sometime after that, he ate like a bird. First you freak over too much and then not enough! Such are the worries of us moms.
B