Offerings

One of the most interesting aspects of Buddhist life is the altar. I personally find someone’s altar one of the best ways to get to know aspects of a person, as the Buddhist altar generally reflects the character of its owner.

For a period of time, my parents had an altar each, and I would do my gongyo and daimoku in front of whichever of the two was free. Comparing the altars meant comparing my parents.

My dad’s altar was always dusty, the fruit was changed very rarely and often became really old and sometimes even moldy, his candle-holders were old and broken.
My father is not a particularly tidy person himself, doesn’t care about appearance and is happy to use old, even broken things as long as they serve the purpose.

My mother’s altar was always clean and sparkly, every object was chosen with care and the disposition was changed often. However, only the bell had been bought in a Buddhist shop, everything else was intended for another use but she liked to use it for her altar. Her fruit was always fresh and the incense holder emptied often. It was beautiful, as everything my mother touches.
My mother, obviously, is a very tidy person who likes surrounding herself with beautiful objects, is very creative and gives new life to old things by re-vamping them and using them in unexpected ways.
My altar? It’s small, like me, and it’s full of green stuff (my favourite colour). I like to think of it as my kosen rufu garden.

As I mentioned time and time again, the only altar item you MUST have is a Butsudan, to protect the Gohonzon. Everything else is an extra and should be left to the taste and desires of the owner. There is no such thing as the perfect altar and if anyone comes to you and criticises the absence of such and such object on your altar (Butsudan excluded, obviously), you would be justified in politely invite them to mind their own business.
An altar has one specific purpose: it’s a place to chant daimoku and gongyo. It should be a  place where you like spending a lot of your time. Pretty objects and offerings can make it pleasant, but they should not distract from its main purpose, which is to chant Daimoku to the Gohonzon.
It should be well lit, the Gohonzon should be at a comfortable height - slightly higher than your line of sight when you’re in a seating position is perfect, so that you keep good posture throughout. It should have a comfortable chair or cushion or stool in front.

That being said, there are some items and offerings which are traditional and you will always find in a Buddhist centre. I already mentioned the Butsugu items before, now I wanted to talk about the traditional offerings and what they mean, so that you know when you compose your perfect (i.e. perfect for you) altar.

Let’s first look at some quotes regarding offerings:
Nichiren Daishonin says: “Whether you chant the Buddha's name, recite the Sutra or merely offer flowers or incense, all your virtuous acts will implant benefits and roots of goodness in your life" (WND 1, 4).
He writes to the disciple Abutsu-bo “you may think you have offered gifts to the treasure Tower of the Thus Come One Many Treasures, but that is not so. You offered them to yourself. […] You should recite Nam-myoho-renge-kyo with this conviction. Then, the place you chant daimoku will become the dwelling place of the treasure tower” (WND 1, 300-1).

Traditionally, the main offerings to the Gohonzon are evergreens, candles and incense.
This triad has a symbolic meaning, it represents the three truths and the three inherent properties to the nature of the Buddha.
These are: 
1. the Dharma body, which indicates the fundamental truth of life, or the Mystic Law; 
2. the reward body, which indicates the wisdom of the Buddha that we develop by chanting Nam-myoho-renge-kyo;
3. the manifest body, which represents the bodhisattva actions to save all people from suffering. (quoted from here.) The incense represents the truth of the Middle Way, the essential property of the life of the Buddha or the property of the Law.

The candles represent the truth of non-substantiality, the spiritual aspect of the Buddha and his wisdom.

The evergreen represents the truth of temporary existence, the the physical aspect of the Buddha and his compassionate actions.
On the topic of which plants to offer specifically, the Daishonin never actually mentioned evergreens, but said that “To recite Nam-Myoho-Renge-Kyo means offering the flower of the treasure to the Buddha” (I translated this from here, but I could not find the source in the Gosho or the Record of the Orally Trasmitted teachings. Any ideas?). Our recitation of Daimoku represents in itself the best offering of the “flower of the treasure”. On the basis of this we offer evergreens, because they symbolise eternity. In Japan they offer shikimi, because it's an evergreen (looks the same throughout the year) and it's aromatic.

As well as the three offerings detailed above, the tradition has to offer to the Gohonzon a small cup of fresh water in the morning, just before morning Gongyo, to be disposed of just before evening Gongyo. The tradition of offering water originates from India, where water was considered precious because of the torrid climate, and it was offered to guests first, and after also to altars and temples.

Finally, another offering is food, particularly fruit (I have seen chocolates or packs of biscuits to be offered as well). Also, ringing the bell is considered an offering.

Nichiren Daishonin talks about the benefits coming from offerings in a Gosho addressed to Nanjo Tokimitsu called “The two types of faith”. In it, the Daishonin tells the story of two youths who met the Buddha Shakyamuni and offered him a mud cake in the absence of a better gift. One of them, thanks to this sincere offering, was reborn as the great king Ashoka.
In the Gosho, the Daishonin writes: “If such a marvelous reward was brought about by the mere offering of a mud pie, how much more will come about as a result of all your various gifts!" (WND, 1, 899)