It depends on the type of organism. In the case of plants, many of which are green, photosynthesis occurs. In the case of some animals, like certain frogs, ingestion occurs.
An organism that can make its own food is an Autotroph.
A multi-cellular green food producing organism would be placed in the Plantae kingdom.
Green plants.
Autotrouphs or green plants
Food chains start with a producer, which is an organism that creates its own food. For example, a plant.
the organism that has green blood is the green tree lizard
Most green plants contain a green pigment called chlorophyll in their leaves. This chlorophyll is responsible for the manufacture of food in plants.
The organism that produces food in the food chain for other organisms is the producer. The producer is usually a green plant that is eaten by an omnivore or a herbivore. And the food chain continues
flowers trees grass lots of plants they do this by using photosynthesis
A organism's niche determines three different things. The three things that are determined are where the organism lives, where it is on the food web and the food the organism eats.
The role of plants in a food chain is as a producer. A producer is an organism that can make its own food through the process of photosynthesis.
At the bottom of any food chain are the producers. Generally producers are thought of as being "green plants". A producer need not be green, (diatoms, red algae brown algae, chemosynthetic bacteria as in the ocean deeps by hot-water vents are examples of non-green producers). The foregoing are not even vascular plants. Perhaps the producer organisms responsible for the greatest food production would be the phytoplankton of the oceans. If an organism is being sought as the occupier of the bottom of a food chain or web, I agree. However, at the bottom of any food chain or web I would place an energy source. The food pyramid sits upon one or several energy sources. It is not an organism, but I believe it must precede any organism capable of synthesizing a food. Perhaps the question now may be, "What was the first energy incorporating organism?"