You can change the flavor of these simple sandwiches by varying the herbs you add to the cream cheese. Any favorites will work well alone or in combination.
Place cream cheese and herbs in a bowl; stir with a rubber spatula until combined.
Spread cream cheese mixture on 4 slices of bread; layer with cucumber and radish slices. Spread remaining slices of bread with butter. Place, butter side facing down, on radishes. Trim crusts; cut sandwiches in half.