During my first year in Japan, I was invited to visit a Japanese coworker's (同僚) house. I wanted to take flowers to show my appreciation (感謝) for her hospitality (厚遇?).
I went to the store and found the flower section (コーナー). There were many beautiful flowers, but I saw some purple-pink flowers that were very cute, and I chose those. I was satisfied that I had a nice small gift for my coworker.
My fiance (now husband) saw the flowers I bought. He told me, "You can't take those flowers! They are for graves (お墓) or Buddhist altars (仏壇）.
I was so surprised! In the U.S. people decorate graves with any kinds of flowers. There are no flowers that would be thought of as only "grave flowers". But I was saved from embarrassment!
I quickly returned to the store and bought some more appropriate (適宜?) flowers!
By the way, here are some American graves with flowers. Different families, cultures, and religions have their own ideas about how and when to decorate graves, but here are some examples.
What kind of flowers do you put on your family tomb (お墓) 
