AE American English ( official american state government website)
Here they offer English teaching forums, Trace Effects Game, Free Textbooks, and other resources.
Other Best Premium English Learning Courses.
Learn Real English by A.J. .Hoge (I strongly recommended this course. Really super)
World’s most famous and easy way to learn English conversation speaking English. It also provides a way to learn grammar.
Espresso english by Shayna Oliveira – (Strongly recommended. Very good lessons to learn American slang)
Their PDF books are really awesome. Definitely, you need to buy and learn this material.
Best to learn grammar by watching videos shooted in England streets. You can watch their videos online without paying any money.
Best American English Dictionary
The New Oxford American Dictionary – Most famous one to learn American English words.
The American Heritage Dictionary: Fifth Edition – If you have already bought NewOxford Dictionary then another choice is this one.
Also, check The American Heritage College Dictionary.