I am not sure about have/had but I think the right way to say it is " I'll tell you what I (have) learned from you " I am not sure about it that's why I am posting this as a reply not an answer. You can also use learnt instead of learned. Learnt is common in British English, learned in American English.
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A DollarIs this sentence all right or not..This tense is called the past perfect. I could be right. It requires that another action took place in the past, but after this one. Without that other action being included, it looks wrong. It is probably not what you meant.
I will tell you what i had learned from you..