Evidently, taking Grant’s advice, the family made their way to San Francisco in 1865 (or 1869). Fannie soon married and began to raise a family. However, an adventurous Nellie, enamored with the gold rush stories of the west, soon hired out as a cook in various Nevada mining camps, including Virginia City and Pioche. After carefully saving her money, she opened the Miner’s Boarding House at Panaca Flat, Nevada in 1872. She was said to have always been a great friend to the miners, often feeding them and providing lodging if they had no money.

Later Cashman would be described as "Pretty as a Victorian cameo and, when necessary, tougher than two-penny nails." And that she was. These few Nevada mining camps would be just some of the first that Cashman would spend time in, always starting a business, doing a little prospecting on the side, and looking after the miners.

In 1874, when gold was discovered in the Cassair Mountains of British Columbia, Canada, Nellie joined up with a group of 200 Nevada miners headed northward. At Telegraph Creek, she set up another boarding house for miners. Again, she looked after the miners, providing help when they needed it and looking after them when they were ill. A devout Catholic, Nellie began collecting money for Sisters of St. Anne in Victoria to build a hospital. Appreciative of her care, they were quick to help.

Sometime later, Cashman traveled to Victoria to deliver $500 dollars in donations, which would help the nuns in building St. Joseph’s Hospital. While there, she heard that 26 miners had been stranded in a snowstorm back in the Cassiar Mountains. Wasting no time, she organized a rescue expedition with six men, and a number of pack animals carrying 1,500 pounds of supplies and took off with the expedition to find the stranded men. Conditions in these mountains were so hazardous at the time, that even the Canadian Army had refused to mount a rescue. When they heard about Cashman’s expedition, the commander sent his troops to find her and return her and the men back to safety. However, when they did find her, she refused to return without the stranded miners.