How to create an environment that flanks its content from the top and from the bottom with lines, the top of which contains a picture in the middle?

Question

I'd like the following code:

\documentclass{article}
\usepackage{lipsum}
% macro definitions...
\begin{document}
\begin{signenv}{A}
\lipsum[1]
\end{signenv}
\end{document}

To produce this:

In words: the signenv environment's paragraph is flanked from the top and from the bottom by two lines the length of the paragraph. In the middle of the top line there's a diamond with a letter inside it. The letter is determined by the mandatory parameter passed to the signenv environment. There's some space between the diamond and the top line.

signenv must not embed the paragraph inside a TeX box/a tcolorbox etc.

Answer 1

\documentclass{article}
\usepackage{lipsum}
\newenvironment{signenv}[1]{%
\par
\smallskip
\noindent\hrulefill\ %
\begin{picture}(20,20)(0,0)
\put(10,0){\makebox(0,0){#1}}
\put(0,0){\line(1,1){10}}
\put(0,0){\line(1,-1){10}}
\put(20,0){\line(-1,1){10}}
\put(20,0){\line(-1,-1){10}}
\end{picture}\ %
\hrulefill
\par
\bigskip}
{\par\medskip\noindent\hrulefill\par\smallskip}
\begin{document}
\begin{signenv}{A}
\lipsum[1]
\end{signenv}
\end{document}