Any ideas on where I can find
 

I was gifted a futon frame that is missing the hardware. It is the little "plugs" that screws go into. Any ideas on where I might find these? I've looked at Lowes and Home Depot but they don't either one have it.

Try a craft department like at JoAnns, Michaels, Hobby Lobby. Sometimes they have wood pieces. You might have to stain them to match the futon.

i find a lot of 'unusual' hardware at Ace Hardware. good luck.

Contact the manufacturer of the futon, it should be on the piece somewhere.

At Home Depot, you head to the area where they have all the wood trim. The wooden plugs are in little bins. Same with Lowe's, head towards the aisle where the trim, the ready to be finish fancy table legs and pillars are. They are in bins and come in packages of 6 or so.
I don't work at either place, but my husband used to be in construction so I know where everything is...lol

The section that carries the wood stuff at Joann's has them - I have purchased them there!

Try a bed store. They might have parts for sale.

Try a wood workers store.