Your attribute should work - probably best handled with CSS though:
<td style="vertical-align:top;padding-top:0;">
you may well be experiencing padding or margins on items within the td, for example <h3> may have a padding-top or margin-top set that will push it from the top of your td so although the td style is working the contents are still subject to their own styles.
as a quick test you could use this in your head to clear all padding-top and margin-top from contents in your tds:
<style>
td *
{
padding-top:0;
margin-top:0;
}
</style>
