How to get Textbox value from dynamic generated onClick EventHandler

The code below generates on the fly multiple Gridviews, TextBoxes, and buttons. For each button a event handler is added like this.b.Click += new EventHandler(ValidateBtn_OnClick). Since ValidateBtn_OnClick is added separately I don't know how to pass the TexBox ClientIDs to it from BindRelatedProductsGrid(). I need  fetch each TextBox Value on the onclick event below: I tried using Request.Forms["..."] , but no success.public void ValidateBtn_OnClick(object sender, EventArgs e)

{

// How to get the value for each generat ...