These can be dug up without the need for the metal detector. Save up on the metal detector and immediately buy it once you have the money. (This would be the tarot cards, American wild flowers, heirlooms, eggs, antique alcohol, and some of the pieces of jewelry) You can filter the map to remove some of the collectibles that you can't pick up for now.
I suggest you search for collectibles that don't require the metal detector for now. You need a metal detector for these items to dig them up with a shovel. Some items have a little icon (the one that looks like a lantern) next to the hint if you're clicking on the items and it shows the hint of the item's location.
I've been using it since I found out about it and have levelled up quickly.
