1 Corinthians 3:9 (NKJV)
9 For we are God’s fellow workers; you are God’s field, you are God’s building.
Notice the change in pronouns, “we” and “you”. We refers to Paul and Apollos (see context, vs. 5,6). Paul and Apollos are fellow workers. The word in Greek is the adjective συνεργός [sunergos /soon·er·gos/ which is often translated helpers. The KJV says, labourers together with God, but “with” is added and not in the Greek. The NKJV translates the better sense, that is, Paul and Apollos are fellow workers of God.
You, the Church in Corinth, are metaphorically God’s field (referring back to vss. 5-8) and God’s building (more on that in vs.10ff). Paul and Apollos are fellow workers of God as they labor in the Church. Paul says Apollos and I are planting in the field and helping construct the building.