Why do we offer food to the Gods? There would be a lot many reasons assigned to this based on the lens we don while answering the question. One way of looking at it is that our Gods are anthropomorphized forms of our fears and uncertainties. For the primitive society dependent completely upon the elements of nature, offerings to the unknown to appease and seek protection from the elements perhaps came naturally. Offering the prime source of sustenance to that all powerful unknown was the best form of appeasement.
Naivedya (नैवेध्य) is a Sanskrit word meaning supplication. It is food offered to a Hindu deity as part of worship, before eating it. Tasting during preparation or eating the food before offering it to God is forbidden. Once, it has been offered and then taken away for consumption, it becomes the ‘Prasad’ – which also means mercy. Hence, most foods offered to the deity are ones that are considered pure and have some symbolic significance. One point here is that naivedya is not just food but any tangible or intangible offering to the Gods.
The most basic naivedya that I have seen in all the pujas done in the family consists of soaked, uncooked rice, 3 or 5 types of fruits, sugar, milk, camphor and honey. The only exception is during Kojagari Lakshmi puja that most Bengali households do on the full moon day right after the Durga Puja. The naivedya here consists of soaked moong daal, grated coconut and sugar. I have seen that a similar naivedyam is offered during the Varalaxmi puja in the Southern states. Which denotes that there has to be some textual reference of moong daal being offered to Goddess Lakshmi. I am still in search of it. Approaching it from a point of symbolism, it is perhaps the fact that moong beans sprout easily even after months of being dry, which shows longevity. Coconut, as we know is considered sacred and beyond its spiritual reasons, is so because it encases embryonic fluid. It is also because all parts of the coconut tree is economically useful.
While the search is on for exact textual reference, the mixture of oaked moong daal, grated coconut and sugar is extremely palatable and I do not mind having it once in a while, and just as prasad.