Yes, I know there is no such thing as "Congregation Appreciation Month." In fact, it is apparently pastor Appreciation Month. Why?
I couldn't find who started it, so I suspect it may have been Hallmark or some other greeting card company to promote their revenue or by some pastor needing to be validated.
Personally, I see no need for a month or a day to be designated for me to be appreciated. My reason is simple and will let the words of Paul the apostle explain it. He wrote to the Thessalonians:
But as we have been approved by God to be entrusted with the gospel, even so we speak, not as pleasing men, but God who tests our hearts. For neither at any time did we use flattering words, as you know, nor a cloak for covetousness--God is witness. Nor did we seek glory from men, either from you or from others, when we might have made demands as apostles of Christ. 1Thes. 2:4-6
I'm with Paul. I have been approved by God in my ministry as well, therefore I speak and serve to please Him, for He will be the one that I will have to stand before and give account. Therefore, the glory of men (being praised and exhalted by men), or by my congregation is not needed or expected, nor demanded.
Paul also has taught me that my joy in ministry is not found by being recognized and applauded by my congregation but by their lives lived for the Lord consistently until His return.
For what is our hope, or joy, or crown of rejoicing? Is it not even you in the presence of our Lord Jesus Christ at His coming? For you are our glory and joy. 1Thes 2:19-20
I can sincerely say, for me to watch my congregation, those God has given to me to serve and teach, take hold of God's truth, to apply it and grow in their relationship with the Lord Jesus, is of great joy to me. The apostle John made similar statements in his 3rd letter.
For I rejoiced greatly when brethren came and testified of the truth that is in you, just as you walk in the truth. I have no greater joy than to hear that my children walk in truth. 3John 3-4
My congregation is a source of "great Joy" to me for they continually demonstrate a walk in God's truth and so demonstrate their appreciation of me as they glorify the Lord in their lives. Lord bless them and keep them.