I found, thanks to twitter-induced serendipity (others call it procrastination), the lyrics of the songs included in the annual Billboard Top-100 from 1965 to 2015 (i.e., considering a few missing, ~5,000 songs). You can find in GitHub, together with the raw data, some clarifications on how the data were collected, their limitations, etc. plus a pointer to a nice analysis already done.
I uploaded on figshare (here) a dataset. From the description there:
This dataset contains 1,093 movie scripts collected from the website imsdb.com, each in a separate text file. The file imsdb_sample.txt contains the titles of all movies (corresponding file names are in the form Script_TITLE.txt).
The website was crawled in January 2017. Some scripts are not present as they were missing in imsdb.com or because they were uploaded as pdf files. Please notice that (i) the original scripts were uploaded on the website by individual users, so that they might not correspond exactly to the movie scripts and typos may be present; (ii) html formatting was not consistent in the website, and so neither is the formatting of the resulting text files.
Even considering (i) and (ii), the quality seems good on average and the dataset can be easily used for text-mining tasks.