What is the easiest mushroom to grow for beginners?

Oyster mushrooms are the easiest to grow. They colonise quickly, fruit on cheap substrates such as pasteurised straw or sawdust, and shrug off minor contamination better than most species. Blue, grey, and pink oysters all suit beginners, and pink oysters do well in warm Indian conditions. Once you have grown oysters, lion's mane and shiitake are reasonable next steps.