Yes, it would be a normal expectation that receipts would be required.
Your mission is not to give the teachers personal gifts. It is to support the school, students, and programs. Your funds should be used to support your mission. The IRS expects that and for you to use good financial practices. Being accountable and able to show where the money went is a basic part of this.
When we did these, we set the amount and a deadline by which teachers had to submit receipts. The teachers then got a reimbursement check. There were no funds given out in advance.
Some groups prefer to use gift cards, but I can't see where that's any different than handing out cash. In our group, it wouldn't meet the reimbursement guidelines.
The PTO of our small private school provides a cash stipend twice a year to each teacher and their aides. We also provide them with a SCRIP gift card of their choice during our annual teacher appreciation luncheon. Unfortunately, I am frustrated with our teachers because the vast majority of the faculty does not participate in our SCRIP or grocery certificate programs which is basically free money for the PTO. We only have one teacher that attends the PTO meetings (our board's teacher rep.) and we have trouble getting the teachers to support the PTO's fundraising efforts in the classroom (i.e. reminders about the pizza fundraiser.) Basically, I feel the PTO is overworked and underappreciated.
My question is: If your PTO offers the teachers a stipend, do you require receipts from the teachers?
Note: 75% of the funds the PTO raises automatically goes to the school to be used at the Principal's discretion. Of the remaining 25% of funds raised for the PTO's use, a little over half is budgeted directly for the teachers (luncheons on half days, teacher appreciation, cash).