Cake Card - You can get the Cake Card at the bakery, whenever you buy your first cake or pie from them (sorry, cookies don't count. . .they don't? AW, MAN!). Note that you have to order from the counter, you can't order form the table. From then on, every time you buy a cake or pie from the counter, the Baker will add a point to your Cake Card (no more than 100 points, though). At the end of the year (the 25-29 of Winter), you can take your Cake Card to the bakery and enter in a raffle. You can buy one ticket per 10 points you have, and if you have filled up your cake card, your chances of winning are very good. I've heard there are 4 prizes, but I still have yet to see them.
Flower Card - The Flower Card is given to you when you buy your first pack of flowers from the Florist Lillia (again, BlueMist Flower Seeds don't count). Like the Cake Card, for every pack of flowers you buy from there on, you can get a raffle ticket during the 25-29 of Winter. It is also 10 points per raffle ticket. Not sure about the prizes, but I can imagine that there are another 4 or so. One thing why the cake card seems to be better is that you can buy like 5 products and give them away, but with flowers you have to grow them outside, which takes time, so basically you can mass-buy cakes and pies, but the flowers are a bad idea.
Lantern - I've yet to see it, but I've heard of it not just from talk, but from the game as well. Not sure what this does, It's apparently for use at the Flower Festival (maybe you'll see Grandpa again, hehe!).
Ocarina - The Ocarina is for sale at the Souvenir Shop at a whopping 1200G. But it's a very nice instrument, don't you think? You use the ocarina at the Spirit Festival (if you're invited). Other than that, you can't play it anywhere else just for the heck of it, so it wasn't exactly a great bargain. But It's still worth buying.
Music Box - The Music box is first found in your field, broken. To find it, follow the map (go west from the doghouse and bury in the spot where you see a tree on the left) to that exact spot, and dig 10 times in that particular spot. You'll dig it up. Then take it to Rick's Tool Shop, and he'll ask you to take a look at it. Then, he'll fix it up for you, and tell you that it's a love song, and you are supposed to give the music box to a girl. So go give it to your girlfriend!
Door To Heaven - No, you aren't dead yet, it's just an old, very fine wine from the Vineyard many years back. You get this from Duke, either by being good friends with him or by wooing Karen, but either way, once you have it, the elves will have a new phrase to say! So do what they tell you and take it to the Harvest Goddess (with a vegetable). Then, make a wish to restore the tree on the Vineyard. You'll restore the tree on the Vineyard, and he'll go get the long lost Keifu Fairies, in charge of making a good harvest. A season or so later, the Harvest Goddess will tell you that the Kiefu Fairies are back, and that day you'll see that everyone living at the vineyard will be out harvesting!
Book - Still wondering if it exists, the probability is highly likely. In the game, you'll get a different gift from whichever girl you are chasing. In Maria's case, she'll give you a book, and tell you take care of it. This doesn't do anything that I've found, but it's a nice momento.
Map - The map can be pulled right out of the tree on your farm, you just, erm, need to have the etiquette to do so! The map reads, "Go straight from the dog house and bury in the place where you see a tree on the left. (your name here), 5 years old, summer." If you dig there, you'll find a music box (read all about it above). Once you have the box, this becomes useless, except to prove that you were once a 5 year old.
Marble - The Marble is still a mystery today! I've heard that you have to grow flowers on the farm to get it, and you don't have to. However, the type of flower is still unknown, and the number of pack is also a mystery. The most outrageous thing I've heard is growing 5 packs of MoonDrop, then 5 of Pink Cat Mint. Well, I did that and it worked, so that should be enough. Once you do that, Stu will come over and ask you to trade with him: a marble for a flower. So trade it, and you've got a marble. Take that marble to the elves, and they'll go nuts when they see it. Then, they'll give you a power berry for your efforts.