Welcome aboard Arthur! I have no idea about the Straits coin - unless it is a serious rarity then grade probably consigns it to curiosity value. Somebody here will know though! The 1864 is a good date, but it's one of those dates that is relatively common in your grade, but becomes one of the most difficult Bun Heads of all in higher grades. The gradient of scarcity (and thus of value) is steeper for the 1864 than for most dates in the series. Incidentally, the 1864 comes in two flavours, the Upper Serif (referring to the shape of the 4), and Crosslet 4 varieties. Yours is the former, and is slightly commoner than the crosslet. I expect you'd be disappointed with what they'd fetch - have a quick look at Completed Listings on ebay.co.uk and you'll get the picture. Keep 'em, I'd say.