Have a look at the --inserts
option of pg_dump
pg_dump -t your_table --inserts -f somefile.txt your_db
Edit the resulting file if necessary.
For a subset, as IgorRomanchenko mentioned, you can use COPY with a SELECT statement.
Example of COPYing as CSV.
COPY (select * from table where foo='bar') TO '/path/to/file.csv' CSV HEADER