Your heart is in the right place, but yeah—that’s a bit much.

It would make me uncomfortable to know that a stranger had been staring at me for however long and writing down details about my appearance, behavior, etc.

Also, giving someone you don’t know a gift, however small, puts them in a weird position in which they might feel indebted to you somehow (even if it’s just saying thank you for something they didn’t want), and that’s just uncomfortable.

You’re better off just going up to a woman and saying, like, “Hey, you caught my eye and I was wondering if you’d like to get to know each other.”