Box around text, image in corner of said box. How do I do it?

This is quite easy with tcolorbox and its overlay feature, placing a node at frame.south east, the node content is an \includegraphics command here.

\documentclass{article}
\usepackage[most]{tcolorbox}
\usepackage{graphicx}
\begin{document}
\begin{tcolorbox}[enhanced,sharp corners,
  width={10cm},
  colback=white,
  overlay={\node at (frame.south east) {\includegraphics[scale=0.1]{ente}};} ]
Sample text here.
\end{tcolorbox}
\end{document}

With a 'blob'

\documentclass{article}
\usepackage[most]{tcolorbox}
\begin{document}
\begin{tcolorbox}[enhanced,sharp corners,
  width={10cm},
  colback=white,
  overlay={\node[circle,fill,red] at (frame.south east) { A };} ]
Sample text here.
\end{tcolorbox}
\end{document}

With blue frame

\documentclass{article}
\usepackage[most]{tcolorbox}
\usepackage{graphicx}
\begin{document}

\begin{tcolorbox}[enhanced,sharp corners,
  width={10cm},
  colback=white,
  overlay={\node[rectangle,draw,blue,line width=10pt] at (frame.south east) {\includegraphics[scale=0.1]{ente}};} ]
Sample text here.
\end{tcolorbox}

\end{document}

In ConTeXt, it is possible to achieve this effect by using Layers and Overlays. In the example below, I define a new frame called cowframe which places a cow at the bottom right corner of the frame.

\setupexternalfigures[location={local,default}]

\definelayer[cowframe][width=\overlaywidth, height=\overlayheight]

\startsetups cowframe
  \setlayer[cowframe]
           [corner={right,bottom}, location={middle,middle}]
           {\externalfigure[cow][height=3\lineheight]}
\stopsetups

\defineoverlay[cowframe][{\directsetup{cowframe}\tightlayer[cowframe]}]

\defineframed
  [cowframe]
  [
    frame=on,
    background=cowframe,
    align={normal,hyphenated},
    width=8cm,
    offset=0.5em,
  ]

\starttext
\cowframe{\input ward\endgraf}
\stoptext

which gives