I can't find any info on harvest festiva

Religous education, I presume. The term harvest festival is a recent invention of some Christian groups to promote an alternative to the Halloween festival, which is of pagan origin. All Saints Day is also a response to the pagan festival Halloween.
I don't think you will find much on Harvest Festival as a Christian celebration, other than what I gave above. It is an invention of "Christian" groups in response to a traditional pagan celebration.
In the US, candy makers are very supportive of Halloween, as it is a major event in their year. Like the floral industry, things which promote economic well being for certain sectors are hard to oppose. Consider flowers at valentines, for instance. And candies also at valentines...
What we need is a healthy food holiday. No alcohol, no fat, no flowers, with good times. I am not optimistic that will happen anytime soon.

It seems like you're asking about information on the harvest festival, specifically in a religious context. While the term "harvest festival" may have been invented by some Christian groups as an alternative to the pagan festival Halloween, it is not as widely recognized or celebrated within Christianity.

If you're looking for information specifically on a Christian harvest festival, it might be challenging to find extensive details or resources on this topic. However, you can try the following approaches to gather more information:

1. Research Christian denominations, particularly those with strong ties to agricultural communities or rural areas. These denominations might have specific traditions or celebrations related to harvest festivals. You can find information about these denominations through their official websites or by reaching out to local churches.

2. Explore the history of harvest festivals in different cultures and religions. While harvest festivals are not exclusively Christian, understanding their origins and practices in various contexts can provide you with a broader perspective. This might involve researching pagan festivals, historical agricultural celebrations, or other religious traditions that incorporate harvest themes.

3. Engage with online forums, discussion boards, or social media groups focused on Christian traditions or religious studies. These platforms can connect you with individuals who have firsthand knowledge or personal experiences of harvest festivals in a Christian context.

Overall, it's important to note that the information on harvest festivals in a Christian context might be limited due to its relatively recent invention and narrow adoption. Exploring different approaches, such as considering historical precedents or consulting with knowledgeable individuals, may help you in your search for more information on this topic.