\documentclass{article}
\usepackage{lipsum, array}
\newcolumntype{L}[1]{>{\raggedright\let\newline\\\arraybackslash\hspace{0pt}}m{#1}}
\begin{document}
\begin{tabular}{lL{.5\textwidth}}
This should stick to the top. & \lipsum[1]
\end{tabular}
\end{document}