Accumulate, gather, as in Go get all the firewood together: [c. 1400]
Come together, assemble, as in Let's get together next week. The variant get together with means "meet with someone," as in I can't get together with them today but I'll have time next week. [Late 1600s]
Arrive at an agreement, as in The jury was unable to get together on a verdict.
get something or oneself together. See under get one's act together.