Adorable straw frames

I spotted this trio of straw frames at an antiques market in Alsace this summer. It looks like we were just in time to prevent an up-cycling project with silver paint! The larger frames measures 61 x 51 cm & the pair 39 x 52 cm each. We love collecting Tramp Art but have never come across anything like these before. They've clearly been used to frame first communion certificates which are in poor condition but the frames themselves (apart from some dirt & that splodge of paint) are in really good order.

I'd love to know if anyone has anything similar and if so what is the best way to clean & care for them. Thanks!