The pink peppercorns you saw at the herb store could be from a pepper tree, but I can't tell you for sure. You should ask if the store manager knows what plant the seeds come from.
Seeds of both the California pepper tree, also called Peruvian Pepper Tree (Schinus molle) and the Brazilian Pepper tree (Schinus terebinthifolius) are poisonous according to the AMA Handbook of Poisonous and Injurious Plants 1985. Eating large amounts of the berries can cause gastroenteritis, vomiting and diarrhea according to another source Poisonous Plants of California, University of California Press, 1986. It states "the red berry like fruit of the Brazilian Pepper Tree sometimes were sold and used as an imported spice called Pink Berries or Pink Peppercorns. No information is available regarding the toxicity of these berries when used in small amounts as a spice". Both trees also can cause contact dermatitis. The symptoms from the Brazilian Pepper Tree are more severe. California Pepper Tree leaves emit a distinct odor of black pepper when crushed. Leaves of the Brazilian Pepper Tree also emit a pepper-like odor but it is not as pronounced as with the California pepper tree.
By V. Lazaneo, Urban Horticulture Advisor, Emeritus, UC Cooperative Extension, August 2012