You should plant after your last frost date. Find your last frost date here: http://agebb.missouri.edu/weather/frost.htm
Depending on how long your growing season is, you may still have to start some seeds indoors to give them a head start or they won't be grown enough to produce fruit before your next frost. If you don't want to start seeds indoors yourself, you can check local stores in the Spring for plants of the things you'd like to grow, like tomatoes, peppers, etc.
As for what to plant, plant varieties you like to eat. The easiest things to grow are tomatoes, peppers, radishes, lettuces and zuchinni.
at 8:10 PM on Jan. 27, 2011