This contains several example data sets:
Textual data from the Stanford Sentiment Treebank: http://nlp.stanford.edu/sentiment/index.html The classes are the original 5 classes.
Textual data from the Stanford Sentiment Treebank: http://nlp.stanford.edu/sentiment/index.html The classes collapse the two positive and negative classes from the original treebank to a single class, so there are three classes: "positive" (1), "negative" (-1), and "neutral" (0).
Textual data from Tomas Mikolov's processed version of the Penn Treebank: https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.1085.9149&rep=rep1&type=pdf