Looks like Tagetes erecta is your plant. I googled something and came up with it. Wiki and Tagetes erecta together should give you what I found. Amazon has them. Apparently they are also known as African Marigolds.

Here is a link that might be useful: seed source

The ones we saw were 4' tall. Looking for seeds thought of Burpee's who championed the marigold and they have an African hybrid called Flagstaff, "the tallest African". That's what I'll get for sowing next year. Thanks for leading me in the right direction chas045.
Nancy

So sorry to hear this news Nancy. I have Day of the Dead Marigold seeds that someone shared in the seed swap years ago. They've been in my fridge all these years so they might still be viable. The packet includes the Aztec or Mixtec name for them, it's long with few vowels. It is garden collected seeds and not a commercial packet. I can bring them up to you one of these weekends.

Restoration Seeds sells a Day of the Dead marigold called 'La Ribera'. Here's the link: La Ribera

-I am very sorry for your loss.

Nancy, I'm so sorry to hear that about your sweet daughter! I still recall the swap she came to and helped distribute all your little sedums in oddball containers! (hugs)