Below is a listing of the first known reference in newspapers to cricket being played by teams starting with the letter Y in various settlements in Wales during the 19th century.
Y Baner 1870
Y Crwydwyr (Wanderers) 1884
Yniscedwyn 1867
Ynispenllwch 1879
Ynysmaengwyn 1881
Ynysmaerdy 1896
Ynysybwl 1896
Ynysygerwn 1846
Youngs of Wainceirch 1856
Ystalyfera 1866
Ystalyfera Juniors 1871
Ystrad 1874
Ystrad and Treherbert 1867
Ystrad and Treorchy 1870
Ystradfellte 1872
Ystradgynlais 1890

Credit – Glamorgan Cricket Archives.
Ystrad Ladies (Denbighshire) 1886
Ystrad Meurig 1860
Ystrad Meurig Grammar School 1862
Ystrad Mynach House 1884

Credit – Glamorgan Cricket Archives.