screw hole plug 5/16 of an inch

Thanks for posting! We have two different options that meat the specifications you need. They are the 67-017 White Snap Cap Screw Covers (sold in packs of 5) and the 67-019 (sold individually). 

Carefully look over each of them to determine if they could work for your and which might be the best option.

Detail of 67-017

Profile view of 67-019