I have to advise against giving children treats if their parents attend the meetings. Apparently before my time our school tried this and there was a HUGE blow up. Lots of trouble. Several parents had to work, had sickness, no car, etc. and were not always able to attend. They were mad because they felt that their children were being punished for something they could not help.
A key to parental involvement (and there are lots of keys) is INFORMATION. Be as informative as you can be, often you feel like you are wasting your time with the newsletters, bulletin boards, web pages, etc., but if you reach one parent it is worth it.
At our PTO meetings we have refreshments (free food!), door prizes for adults and children (usually from the Dollar Store or donated), day care (a local homemakers group volunteer their time), and the teachers from each hall with the most parents attending get a banner and a supply basket (worth about $15). This helped us with attendence.
There is nothing wrong with begging.