So long as the stamps add up to the amount of postage needed from the US to Brazil, you're fine. Currently, domestic Forevers are worth 55 cents and global Forevers are $1.15. So you could use two domestic Forevers plus a five-cent stamp to make the rate of one global Forever, for example.

Hi jewels1 :)

You can buy US stamps here: https://www.amazon.com/gp/product/B071V7K5JS/ref=as_li_tl?ie=UTF8&tag=fanmailbiz-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B071V7K5JS&linkId=9e190eb8eb44b3e3d326e91a3532aa62

Global Forever Stamp (Green Succulent) Can be Used to Mail A One-ounce (28.3 g) Letter to Any Country to Which First-class Mail International Service is Available

Fanmail 8)

Hello, I wanted to know which stamps I can use for SASE (for the US), what are the current ones? Can I use the birds of each state? the US flag, and where can I buy without needing an international card? ( I'm from Brazil )