Put the almonds in a toaster oven or regular oven and bake at 350 degrees until they are golden brown for about 10 minutes.
Butter a casserole dish (such as an 8-8-inch square baking pan).
Put 2 cups of water on to boil with 1 tbs salt.
When it boils, add rice, cover, reduce heat and simmer about 15 minutes.
Turn the heat off and let sit for 20 minutes.
Melt fat in a wide skillet over medium-high heat.
Chop celery into small dice.
Add to the fat along with the mushrooms.
Increase heat to "high" and cook, stirring occasionally, until mushrooms begin to brown and all the liquid they give up has evaporated.
Shake flour over skillet and stir to blend as evenly as possible with the vegetables.
Add the broth in a slow stream.
The flour will seize into a tight mass but keep adding liquid and stirring; it should relax.
Add the milk, tarragon, turkey, pimento and pepper.
Stir until the mixture boils, then remove from heat.
Combine with rice in the prepared casserole; sprinkle with almonds and bake 15 minutes, or until heated through.
Ready in 50 min.