I was doing some research on Pentecost, got out my "Jewish Holidays" book.

It refered me to Deuteronomy16:9-10

"Seven weeks shalt thou number unto thee: begin to number the seven weeks from such time as thou beginnest to put the sickle to the corn. And thou shalt keep the feast of weeks unto the LORD thy God with a tribute of a freewill offering of thine hand, which thou shalt give unto the LORD thy God, according as the LORD thy God hath blessed thee:"

Seems pretty clear to me - When the harvest of the corn starts, then start counting 7 weeks from that point.

New problem - when did/does the harvest of the corn start?

YBIC, John...  :)