There is a Richard Eddy b1871 St Just on the 1881 census for St Just with parents Richard and Sarah. Richard snr is a Tin and Copper Miner and was born c1843 St Just.
The 1851 census shows this Richard 1843 aged 8 with parents Richard Eddy born c1815 St Just and Mary Ann (probably Walls) born c1821 St Just.There is a marriage of Richard and Mary Ann 25 July 1840 St Just.
Are these the Eddys you are searching for or is this another family?