I have a project which requires a corpus of conversational English in plain text (although I can perform some processing as needed). Since I am a student, I need to find a corpus that is free and downloadable. I would appreciate it if someone could provide suggestions for such corpora.
There are many spoken English corpora available. But generally, you need to ask more questions than 'plain text' before you find the right one. Length, level of annotation, format of annotation, type of conversation, genre/register, dialect, natural vs. elicited, etc. Those will all depend on the type of research questions you want to answer.
If you just want any one corpus you could try:
Santa Barbara Corpus of Spoken American English: http://www.linguistics.ucsb.edu/research/santa-barbara-corpus#Contents
CHILDES collection of corpora (most is conversation) - http://childes.psy.cmu.edu/
BASE - British Academic Spoken English http://www2.warwick.ac.uk/fac/soc/al/research/collect/base/
Here you can find the Saarbrücken Corpus of Spoken English (SCoSE):
I had success with the conversation transcripts provided by UNC Charlotte.