在英文中，"他向妈妈道谢"可以用以下几种表达方式表示：

He thanked his mother.
他向他的妈妈谢谢。
He expressed his gratitude to his mother.
他向他的妈妈表示感谢。
He showed his appreciation to his mother.
他向他的妈妈表示感激。

"Thank"是英文中常用的道谢的词，它的意思是"感谢"或"谢谢"。它来自古英语"þancian"，意为"感谢"或"谢谢"。

下面是一些例句，希望能帮助你理解这个表达的意思：

Thank you for your help.
谢谢你的帮助。
I want to thank you for everything you've done for me.
我想感谢你为我所做的一切。
Thank you for having me over for dinner.
谢谢你让我来共进晚餐。