Dorothy:
I would definitely let the gas company remove these trees for you since NOBODY is going to pay you to remove yard trees.
You can try to sell the merchantable portions (i.e., logs) after the gas line cuts them down for you; simply ask the gas company to leave the larger log portions. Granted, they may balk at this request.
Contact your local California Cooperative Extension office for a list of custom sawmill operators or woodworkers:
http://ucanr.edu/sites/forestry/Staff/County-based_Forestry_Advisors/
Best of luck!