I would have to give a vote for the sand or wild plum where the plums are the size of a quarter and grow on bushes in thickets. Gotta love pomegranate, especially since they have a festival here where I live. The old standby's are great; peach, apricot, grape, etc. If I had to pick just one, I guess it might be possum grape, small wild grape in Oklahoma where I grew up. Seem to be hard to find anymore, my mom used to put a leaf off these in some homemade dill pickle that processed in the sun. Although, there is a recipe for peach pit jelly that is great and pretty cool looking...ah who am I kidding, I like it all!
edited for spelling