I completely understand the desire to work from home to spend more time with your kids... I have had such a terrible time leaving my daughter to return to work (she is 8mo old).
I don't know that much about grants, but there is a government website http://www.grants.gov/ that you might find helpful. I know that minority and women-owned businesses are eligible for financial assistance that may not be available to everyone. However, just a word of caution, if the "grant" is more of an investment in your business (such as from a capital investment firm or the like), then there may be strings attached leaving the "grantor" to have rights over certain aspects of your company. It would be worthwhile to get an attorny to look over any contract that is involved with any grant or investment money.
Another avenue might be to go after a loan instead of a grant. For that you might check out the Small Business Administration http://www.sba.gov/ - this is another government agency set up to support small businesses. Specifically, their section on financing http://www.sba.gov/financing/index.html might be helpful. They have a wealth of other information, too. They have a free educational section http://www.sba.gov/training/courses.html that has online courses about startup, financing, taxes, etc. Anyway, I think it's a good source of information other than just financial assistance.
I wouldn't say that there are no true grants, but there are very few and it is very difficult to get them (unless, apparently, you are doing some absurd study about fast food being fattening or some other nonsense that we already know... but, wait, that's a personal rant of mine...). The library can help you do grant research. However, I think that most of their information is now available through the first website I gave you.
It's great that you already have your idea for your business. I've been wracking my brain to try to figure out what kind of service or product I could provide and stay at home with my daughter.
I wish you the best of luck. Please feel free to email me anytime. I don't have all the answers (ok, so really, I have very few of the answers!) but I'm always willing to pass along anything I've found out. The more we share, the further ahead we all get!