In a medium bowl, combine minced radishes, poppy seeds, cream cheese, and salt; blend well.
Spread one side of each piece of bread lightly with butter. Top the buttered side of 4 slices of bread with radish mixture (about 1/4-inch thick). Top with arugula, spinach, or radicchio leaves and then top with the remaining bread slices, buttered side down.
Carefully cut the crusts from each sandwich with a long, sharp knife. Cut the sandwiches in half diagonally and then cut in half again. If desired, decorative shapes can be made with cookie cutters.
Yields 4 whole sandwiches or 8 halves or 16 fourths.
Making Sandwiches Ahead of Time:
If you need to make tea sandwiches in advance and need to keep them from drying out, cover them loosely with a sheet of wax paper and then place a damp kitchen towel over the wax paper (never place a damp towel directly on top of the bread because the sandwiches will become soggy). Refrigerate.
When ready to serve, remove from refrigerator. Uncover sandwiches just before serving.
* Radishes are usually sold with their leaves attached. Look for bunches of radishes with crisp green leaves. Also choose the ones that the radish globe that are 1 inch or less in diameter to assure a mild flavor and not a woody texture. Radishes will keep in the refrigerator for up to 2 weeks wrappped in a damp cloth or perforated plastic bag.
** Choose the best-quality white or wheat bread as possible. Never serve end slices. Freezing the bread before cutting and then spreading makes for easier handling.
Radish Poppy Seed Tea Sandwich Recipe: https://whatscookingamerica.net/Sandwich/RadishPoppyseedSandwich.htm