I came across Marshall Squares™ on the Kadon Gamepuzzles website in January, 2007.

These are made with 5 colors, with at most 2 sharing a tile equally, and there are 25 of them.

An obvious arrangement of them is into a 5x5 square, with the
edges matching. That is quite difficult, as there are only 16
different ways to do it (not counting rotations, reflections, and color
swaps).

See them HERE.

If we move the corner squares to centers of the edges,
as in the figure at the right, the task is __much__ easier.
Then there are nearly *fifteen hundred times* as many ways
to fit the 25 squares together -- 23558 to be exact.

Here is a sample of them:

the first one has the 'butterfly' or 'argyle' pieces
clustered in 3 groups.

the second one has four of the solids in the extremities and each color forms a continuous path through the figure.

These two are rotated 45° to show their striking symmetry.

the second one has four of the solids in the extremities and each color forms a continuous path through the figure.

These two are rotated 45° to show their striking symmetry.