I recommend the following websites for Harvest Moon information:
Bokumono is the Official HM Website written in Japanese.
Natsume is the company that does the North American localization of Harvest Moon and translates the game from Japanese to English.
Blame them for the bad grammar & typos of almost every Harvest Moon game released in English. (Kidding)
To get the latest news on Harvest Moon games coming to America.
THE BEST Harvest Moon fansite ever created. I have been using fogu for its elaborate Harvest Moon strategy guides. It is currently at its 11th anniversary. Back then, I was first introduced to this website by a friend (who also introduced me to HM) when I was around 10/11 years old. I've been a visitor & forum member of that site 7 years since then, so I have been a follower for a really long time. There is also a forum that you can join and talk about anything Harvest Moon related. My username there is harvestmoonfan13. I don't really post or talk much in the forums, but I always lurk around for answers.
Harvest Moon Otaku. Another good fansite for strategy guides.
And another HM fansite called Harvest Moon Farm.
Ranch Story (the original Jp. name of HM). In my opinion, it lacks substance and details, but the layout looks cute.
Check out KHInsider if you want to hear Harvest Moon video game music.
AWWYEAHHARVESTMOON - A tumblr blog filled with Harvest Moon fan art. REALLY GOOD STUFF.
HarvestMoonHeadCannons - tumblr blog with Harvest Moon fanart.
Note: I am in no way affiliated with these websites or blogs. I am just promoting them.