GOOG or Yahoo, is your friend:
Growing Fall Vegetables
Just an example, from the web, and experience...the prob in 'fall', or even early Sept, is that seed germination is often slow to retarded this time of year. So, gardeners often start 'fall' veggies from seed, a couple weeks ago to a month or so ago, depending on species, and the transplant now. But, some good ideas in that list, and other lists on the web...hard to beat the leafy stuff, which will taste spectacular in late Oct/early Nov.
Your Zone/altitude will have considerable influence on your selections, and success.
As for pumpkins, most varieties have a 125-150+ days time frame, so go buy a punkin in Oct, and don't try to grow any now.
GL, mD
PS... the Garden Forum on this site, City Data, has a very knowledgeable group of posters and an almost encyclopedic depth of 'garden' threads, via Search that Forum.