The straightforward way can be this (obviously, you will define macros for the boxes, but this is to give an idea), using basic LaTeX boxes:
\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\begin{document}
\parindent=0pt\relax % no indent at the start of the paragraph
\fbox{\parbox[t][3cm][c]{5cm}{
Some text
}}\hspace{0.5cm} %% this is the horizontal separation
\fbox{\parbox[t][3cm][c]{5cm}{
Some text
\[ f(x) = formula \]
}}
\vspace{0.5cm} % and this the vertical one --- notice you star a paragraph here (blank lines)
\fbox{\parbox[t][3cm][c]{5cm}{
Some text
}}\hspace{0.5cm}
\fbox{\parbox[t][3cm][c]{5cm}{
Some text
}}
%% repeat as needed
\end{document}
which results in

Or ...
\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\parindent=0pt\relax
\newcommand{\mybox}[1]{\fbox{\parbox[c][2cm][c]{3cm}{#1}}}
\begin{document}
Text \mybox{some text} \quad \mybox{$f(x)$} more text
\bigskip
Text \mybox{some text} \quad \mybox{yeap} and more text
\bigskip
To align it \mybox{you have} \quad \mybox{to use} a tabular or similar...
\end{document}
Which gives:

Obviously, you can use the package tcolorbox for a MUCH better look... just read the manual and try!

tabular. I'll add an answer. – Ruben Apr 11 '16 at 18:39