One may not mix with the grasspea, these are the words of R' Meir. But the Sages permit [it], because it is possible.

[If] a householder is traveling from place to place and needs to take leket, shich'chah, peah, or maasar ani, he may take them, but when he returns to his house, he repays; these are the words of R' Eliezer. But the Sages say: He was a poor man at that time.