Grass Roots - (adjective + noun)
The grass-roots of an organisation or movement are the ordinary people who form the main part of it, as opposed to the leaders. They are also known as ‘the rank and file’. It can be used as both a noun and an adjective.
Source: Adapted from Collins English Dictionary.
Example of Use: The General Secretary said she wanted to see more involvement of the grass-roots members of the trade union.