Thomas Coldwell built the first lawn mower in America, around 1852. His company was ultimately bought out by the Toro Company of Minneapolis, Minnesota. For some interesting history on his machine, visit the Antiques Digest--Lost Knowledge from the Past.
According to the R.E. Olds Transportation Museum, the Ideal Gas Engine Company was formed in 1907, but merged in 1910 with the Air Cooled Motor Company, with R.E. Olds as President. It became the Original Gas Engine Company in 1912. The Ideal Power Lawn Mower Company was founded in 1922 to market their gas powered lawn mower of 1914, based on an R.E. Olds patent. They also produced a riding version, the "Triplex" in 1922, the world's first lawn tractor. The company continued in business until 1945 when it was sold to the Indian Motorcycle Company.
The Jacobsen Manufacturing Company was founded by Oscar Jacobsen in 1921 to produce his "Four Acre Mower" which reputedly was able to cut 4 acres per day on "the vast estates of millionaires." The company was taken over by Textron and now produces mowing equipment under the Ransomes Jacobsen label.The U.S. headquarters are in Charlotte, North Carolina. Their original manufacturing complex in Racine was built by the Mitchell Motor Car Company, and also used as Nash and Massey Harris plants. It was razed in 2005.