"Teacher's Luncheon" means that only one teacher could attend. "Teachers' Luncheon" denotes the plural form, i.e. a luncheon for many teachers.
Luncheon is a noun.
When lunch is served to several people it can be called a luncheon.
It would be unwise to decline an invitation to attend a luncheon with the Queen. In America, plain old baloney is sometimes labelled as luncheon meat. Will you join me for a pleasant luncheon?
The plural form for the noun luncheon is luncheons.
Luncheon on the Grass
I will be going to a business luncheon tomorrow with our new clients.
Luncheon of the Boating Party was created in 1881.
A luncheon is just a fancy lunch, usually with guests.I can give you several sentences.The Ladies' Association held a luncheon at the church.I am going to the group luncheon because they are having a speaker talk about his travels to Egypt.Let's have a luncheon and charge a fee so we can raise money for the band!
If the luncheon is a special event such as a luncheon before a wedding then yes, bring a gift. If it is just an informal luncheon with either friends (no special reason) or business you do not need to bring a gift.
Places manufacturing luncheon meat are covered in SIC 2013
Stock Exchange Luncheon Club was created in 1898.
Stock Exchange Luncheon Club ended in 2006.