My son did this too, seems normal for this age.
Putting things in their mouth is normal, but obsessing over it and. Trying to sneak things when they know they're not supposed to even if you're in sight might be a sign of pica. Easy enough to get checked for peace of mind
I used to eat outside flowers til I was 10 lol just try to give her stuff that is edible that is similar to the things she wants to eat if she likes crunchy stuff maybe meringue cookies? I know I seen someone on TikTok buying stuff similar to the non edible foods her daughter eats
I think all children do this and you literally do just need to follow her around all day if she's somewhere that isn't baby proofed. Both of mine required a lot of 'don't put that in your mouth' and 'that's not a food '. My youngest is 2 and is generally fine about not putting things in her mouth, but I still wouldn't leave her unattended with choking hazards. So, good news: it doesn't last forever.