This pair of stones are just one part of an interesting area on the banks of the River Lyon. Close by is a cup-marked stone, a long cairn, a medieval moated site (once thought to be a Roman camp) and a round cairn topped with a cup-marked standing stone.
Only one stone now stands, while 5m to the NE the second is partly buried, with only a metre of it visible. In 1838, the cup-marked stone which now lies on top of the nearby Lyon Bridge round cairn (supposedly Pontius Pilate's grave!) was actually close to these two stones, having apparently fallen at the end of the 18th century. This has led to suggestions this might be the remains of a four-poster.
However, the same cup-marked stone is supposed to have stood upright on the cairn on which it now lies, and the New Statistical Account actually says "two obelisks, the one about 6 feet high: the other lying on the ground, having been undermined some fifty or eighty years ago". This makes me think that perhaps the half-buried stone might be cup-marked on one of its buried faces, and that it was confused with the stone on the cairn which did once stand there.
Directions - Head N from Perth on the A9 (sign-posted Inverness). After approximately 30.0km, there is a turn-off to the right (a major junction) onto the A827 for Aberfeldy. Take this turn-off, which curves round and crosses over the A9 to the W. Drive through Logierait, and after about 4.5km turn right at the junction (sign-posted Aberfeldy). This road takes you right to Aberfeldy. Carry on straight into Aberfeldy until you reach a cross-roads with a set of traffic lights. Turn right here, onto the B846, which you follow for about 8.0km, until you see the turn-off to the left for Fortingall. Take this road, which winds its way to the village of Fortingall. Carry on straight through the village, past the turn-off to the right for Glen Lyon. Approximately 200m beyond the turn-off is the gate into the field. There's room for careful parking on the verge here. Enter the field, and walk S past some old bits of machinery and various rubbish. Once in this field, you'll be able to see the standing stone in the next field, which should only be entered if there's no livestock in it.