He gave him a bag of rice; can he give zakat al-fitr from it?

Praise
be to Allah 

There is nothing wrong with you giving zakat al-fitr on
behalf of yourself and your family from that bag of rice which you received
as a gift, because the gift becomes the property of the one to whom it was
given, which he may dispose of however he wishes, whether that is selling
it, giving it away, giving it in charity and the like. This has been
explained previously in the answer to question no. 70272. 

Indeed the scholars (may Allah have mercy on them) stated
that if a poor person accumulates from the zakaah of the rich more than he
and his dependents need, he may give zakat al-fitr from that zakaah that
came to him. 

Shaykh Ibn Baaz (may Allah have mercy on him) was asked: If a
poor person receives zakaah al-fitr from people, can he give his own zakaah
al-fitr from that which was given to him, or is that not permissible? 

Answer: 

Yes, he may do that, if what he was given came to him before
Eid, he (may give his zakat al-fitr from it). But if what he was given does
not come to him until after Eid, he does not have to do anything, if he is
poor and does not have anything on the night before Eid; that is, if he does
not have a saa‘ to give on his own behalf or more than that to give on
behalf of himself and the members of his household, because of the severity
of his poverty. Then in that case he does not have to do anything, but if he
is well off enough to be able to give a saa‘ on his own behalf and other
saa‘s on behalf of the members of his household, he should keep enough to
meet his own needs on the day of Eid and the night of Eid, and give zakat
al-fitr from the remainder on behalf of himself and of the members of his
household.

End quote from Fataawa Noor ‘ala ad-Darb by Ibn Baaz
(15/291) 

And Allah knows best.