A 45 year-old homeless female is found unconscious in the street. Her urine drug screen is positive for heroin. She is febrile and when she awakes she notes that she has been having problems with chest pain, shortness of breath and a cough. Physical exam reveals a high-pitched holosystolic murmur heard best at the apex, dark red lesions in the nailbeds and diffuse petechiae. Histology of her damaged heart valve would most likely show which of the following?