This is a huge problem in lots of schools. If you are in district that is large there is bound to be a school nearby to "partner" with for some things.
If you want to pursue the "Dinner Night" (spaghetti or otherwise) get the other school on board and hold one big dinner- they provide some things and you provide others (the paper goods or Tea or bread or whatever). Also approach a local restaurant or grocery store to help you with "in kind" donations. Offer to post their banner or a sign publicly thanking them for their support. Then it is coming out their advertising budget (not as a straight donation) and they might be more willing to give you something. Also stress the fact they will be reaching two schools full of people.
Try to hold the costs down- no more than $5.00 a person (the cost of a fast food meal). Keep to simple- maybe spaghetti, or chilli, or soup and salad night). They will get a fullfilling meal cheaper than they could make it at home. Consider a bundle price for families.
If you want something else simple- the trash to cash is always good- Boxtops, Capri Sun (this is new one I just heard about), Tyson Chicken etc. Also the Cartridge thing really takes off. Ask businesses in the area if you can place a collection box in their office- and someone goes periodically and picks them up.
You will have lots in a short amount of time.
Penny collections are easy and something everyone can do.
Also remember to let parents know that you value THEM and their time. Even if they can not support a regular fundraiser (and I really think you should forego those in high poverty areas) and the "donation of time" means more than anything. Break up jobs into small "bites of time" that parents with multiple jobs can participate in (15 minute reading times, or running copies etc.) then thank them for their truly valuable donation!
What about Scrip? Even with a high poverty level, odds are good that your families are still buying necessary items. If they buy them using scrip cards, your pto can make some funds off of it without asking anyone to buy anything extra.
Also, push programs like BoxTops, and restaurant fundraisers since those aren't dependent solely on your own families.
I don't know where you are but have you tried hooking up with local businesses and doing on going fundraisers. Some easy fundraising opportunities are the local supermarket/grocerey stores. Many supermarkets will contribute 1% or more for grocerey receipts. Another is a recycling program for ink cartridges, laser cartidges and cell phones. The best thing is you aren't selling anything just collecting! It does add up!
Also here is a list of businesses and Stores that give back to the community through fundraising opportunities, grants or scholarships. I hope this helps
Stores That Give Back To The Community
The easiest thing we have done in our low income school is cookie dough. I realize you may have preconceived notions on cookie dough but it's all in who supplies you and how it is distributed. In our school of 1000 kids, we profited $12,000. If you tell me what city you are in, I can put you in touch with the people who handle our sale.
We did one last year and made $3500 in a day. The nice thing about this fundraiser, is that the people paying are from the community, not parents. All you need is space for people to bring their stuff and crop. We had 2 people per 8 ft table. So, if you have the space and tables, it can be very easy.