Massekhes Peah talks extensively about the amount of crop to be left by the farmer for Leket & Peah as well as what constitutes shikhiha.
Some one just asked me if there was a limit to the amount that any one ani could gather of any of Shikhiha Leket and Peah. Meaning, if there is an ani who wants to take all of the peah from a single field is that ok? My gut is telling me that there is a limit but I havent found it.