U by Kotex (limit 2 sample requests per household.) As of this writing, there was a pad sample, tampon sample, and liner sample available.
Equate maxi pad sample. This is a Walmart brand item. Also, sign up for their program for special offers and coupons.
Poise liner and pad samples
Tena samples. There are four kits to choose from.
No samples, but print coupons to save: